// SPDX-License-Identifier: MIT
// File: @openzeppelin/contracts/utils/Context.sol


pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/math/SafeMath.sol


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol


pragma solidity >=0.6.0 <0.8.0;




/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) public {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: @openzeppelin/contracts/utils/Address.sol


pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol


pragma solidity >=0.6.0 <0.8.0;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/BIFI/interfaces/common/IUniswapRouterETH.sol


pragma solidity ^0.6.0;

interface IUniswapRouterETH {
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);

    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);

    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);

    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);

    function swapExactTokensForTokens(
        uint amountIn, 
        uint amountOutMin, 
        address[] calldata path, 
        address to, 
        uint deadline
    ) external returns (uint[] memory amounts);

    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);

    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
}

// File: contracts/BIFI/interfaces/common/IUniswapV2Pair.sol


pragma solidity ^0.6.0;

interface IUniswapV2Pair {
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function burn(address to) external returns (uint amount0, uint amount1);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
}

// File: contracts/BIFI/interfaces/sushi/IMiniChefV2.sol


pragma solidity ^0.6.0;

interface IMiniChefV2 {
    function poolLength() external view returns (uint256);
    function userInfo(uint256 _pid, address _user) external view returns (uint256, uint256);
    function pendingSushi(uint256 _pid, address _user) external view returns (uint256);
    function deposit(uint256 pid, uint256 amount, address to) external;
    function withdraw(uint256 pid, uint256 amount, address to) external;
    function harvest(uint256 pid, address to) external;
    function withdrawAndHarvest(uint256 pid, uint256 amount, address to) external;
    function emergencyWithdraw(uint256 pid, address to) external;
    function rewarder(uint256 pid) external view returns (address);
}

// File: contracts/BIFI/interfaces/sushi/IRewarder.sol


pragma solidity ^0.6.0;

interface IRewarder {
    function poolLength() external view returns (uint256);
    function userInfo(uint256 _pid, address _user) external view returns (uint256, uint256);
    function pendingToken(uint256 _pid, address _user) external view returns (uint256);
    function deposit(uint256 pid, uint256 amount, address to) external;
    function withdraw(uint256 pid, uint256 amount, address to) external;
    function harvest(uint256 pid, address to) external;
    function withdrawAndHarvest(uint256 pid, uint256 amount, address to) external;
    function emergencyWithdraw(uint256 pid, address to) external;
}

// File: @openzeppelin/contracts/access/Ownable.sol


pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/utils/Pausable.sol


pragma solidity >=0.6.0 <0.8.0;


/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () internal {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: contracts/BIFI/strategies/Common/StratManager.sol


pragma solidity ^0.6.12;



contract StratManager is Ownable, Pausable {
    /**
     * @dev Beefy Contracts:
     * {keeper} - Address to manage a few lower risk features of the strat
     * {strategist} - Address of the strategy author/deployer where strategist fee will go.
     * {vault} - Address of the vault that controls the strategy's funds.
     * {unirouter} - Address of exchange to execute swaps.
     */
    address public keeper;
    address public strategist;
    address public unirouter;
    address public vault;
    address public beefyFeeRecipient;

    /**
     * @dev Initializes the base strategy.
     * @param _keeper address to use as alternative owner.
     * @param _strategist address where strategist fees go.
     * @param _unirouter router to use for swaps
     * @param _vault address of parent vault.
     * @param _beefyFeeRecipient address where to send Beefy's fees.
     */
    constructor(
        address _keeper,
        address _strategist,
        address _unirouter,
        address _vault,
        address _beefyFeeRecipient
    ) public {
        keeper = _keeper;
        strategist = _strategist;
        unirouter = _unirouter;
        vault = _vault;
        beefyFeeRecipient = _beefyFeeRecipient;
    }

    // checks that caller is either owner or keeper.
    modifier onlyManager() {
        require(msg.sender == owner() || msg.sender == keeper, "!manager");
        _;
    }

    /**
     * @dev Updates address of the strat keeper.
     * @param _keeper new keeper address.
     */
    function setKeeper(address _keeper) external onlyManager {
        keeper = _keeper;
    }

    /**
     * @dev Updates address where strategist fee earnings will go.
     * @param _strategist new strategist address.
     */
    function setStrategist(address _strategist) external {
        require(msg.sender == strategist, "!strategist");
        strategist = _strategist;
    }

    /**
     * @dev Updates router that will be used for swaps.
     * @param _unirouter new unirouter address.
     */
    function setUnirouter(address _unirouter) external onlyOwner {
        unirouter = _unirouter;
    }

    /**
     * @dev Updates parent vault.
     * @param _vault new vault address.
     */
    function setVault(address _vault) external onlyOwner {
        vault = _vault;
    }

    /**
     * @dev Updates beefy fee recipient.
     * @param _beefyFeeRecipient new beefy fee recipient address.
     */
    function setBeefyFeeRecipient(address _beefyFeeRecipient) external onlyOwner {
        beefyFeeRecipient = _beefyFeeRecipient;
    }

    /**
     * @dev Function to synchronize balances before new user deposit.
     * Can be overridden in the strategy.
     */
    function beforeDeposit() external virtual {}
}

// File: contracts/BIFI/strategies/Common/FeeManager.sol


pragma solidity ^0.6.12;


abstract contract FeeManager is StratManager {
    uint constant public STRATEGIST_FEE = 112;
    uint constant public MAX_FEE = 1000;
    uint constant public MAX_CALL_FEE = 111;

    uint constant public WITHDRAWAL_FEE_CAP = 50;
    uint constant public WITHDRAWAL_MAX = 10000;

    uint public withdrawalFee = 10;

    uint public callFee = 111;
    uint public beefyFee = MAX_FEE - STRATEGIST_FEE - callFee;

    function setCallFee(uint256 _fee) public onlyManager {
        require(_fee <= MAX_CALL_FEE, "!cap");
        
        callFee = _fee;
        beefyFee = MAX_FEE - STRATEGIST_FEE - callFee;
    }

    function setWithdrawalFee(uint256 _fee) public onlyManager {
        require(_fee <= WITHDRAWAL_FEE_CAP, "!cap");

        withdrawalFee = _fee;
    }
}

// File: contracts/BIFI/strategies/common/StrategyMiniChefLP.sol


pragma solidity ^0.6.0;










contract StrategyMiniChefLP is StratManager, FeeManager {
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    address constant nullAddress = address(0);

    // Tokens used
    address public native;
    address public output;
    address public reward;
    address public want;
    address public lpToken0;
    address public lpToken1;

    // Third party contracts
    address public chef;
    uint256 public poolId;

    uint256 public lastHarvest;
    bool public harvestOnDeposit;

    // Routes
    address[] public outputToNativeRoute;
    address[] public rewardToOutputRoute;
    address[] public outputToLp0Route;
    address[] public outputToLp1Route;

    /**
     * @dev Event that is fired each time someone harvests the strat.
     */
    event StratHarvest(address indexed harvester);

    constructor(
        address _want,
        uint256 _poolId,
        address _chef,
        address _vault,
        address _unirouter,
        address _keeper,
        address _strategist,
        address _beefyFeeRecipient,
        address[] memory _outputToNativeRoute,
        address[] memory _rewardToOutputRoute,
        address[] memory _outputToLp0Route,
        address[] memory _outputToLp1Route
    ) StratManager(_keeper, _strategist, _unirouter, _vault, _beefyFeeRecipient) public {
        want = _want;
        poolId = _poolId;
        chef = _chef;

        require(_outputToNativeRoute.length >= 2);
        output = _outputToNativeRoute[0];
        native = _outputToNativeRoute[_outputToNativeRoute.length - 1];
        outputToNativeRoute = _outputToNativeRoute;

        // setup lp routing
        lpToken0 = IUniswapV2Pair(want).token0();
        require(_outputToLp0Route[0] == output);
        require(_outputToLp0Route[_outputToLp0Route.length - 1] == lpToken0);
        outputToLp0Route = _outputToLp0Route;

        lpToken1 = IUniswapV2Pair(want).token1();
        require(_outputToLp1Route[0] == output);
        require(_outputToLp1Route[_outputToLp1Route.length - 1] == lpToken1);
        outputToLp1Route = _outputToLp1Route;

        reward = _rewardToOutputRoute[0];
        require(_rewardToOutputRoute[_rewardToOutputRoute.length - 1] == output, '_rewardToOutputRoute != output');
        rewardToOutputRoute = _rewardToOutputRoute;

        _giveAllowances();
    }

    // puts the funds to work
    function deposit() public whenNotPaused {
        uint256 wantBal = IERC20(want).balanceOf(address(this));

        if (wantBal > 0) {
            IMiniChefV2(chef).deposit(poolId, wantBal, address(this));
        }
    }

    function withdraw(uint256 _amount) external {
        require(msg.sender == vault, "!vault");

        uint256 wantBal = IERC20(want).balanceOf(address(this));

        if (wantBal < _amount) {
            IMiniChefV2(chef).withdraw(poolId, _amount.sub(wantBal), address(this));
            wantBal = IERC20(want).balanceOf(address(this));
        }

        if (wantBal > _amount) {
            wantBal = _amount;
        }

        if (tx.origin == owner() || paused()) {
            IERC20(want).safeTransfer(vault, wantBal);
        } else {
            uint256 withdrawalFeeAmount = wantBal.mul(withdrawalFee).div(WITHDRAWAL_MAX);
            IERC20(want).safeTransfer(vault, wantBal.sub(withdrawalFeeAmount));
        }
    }

    function beforeDeposit() external override {
        if (harvestOnDeposit) {
            require(msg.sender == vault, "!vault");
            _harvest(nullAddress);
        }
    }

    function harvest() external virtual {
        _harvest(nullAddress);
    }

    function harvestWithCallFeeRecipient(address callFeeRecipient) external virtual {
        _harvest(callFeeRecipient);
    }

    function managerHarvest() external onlyManager {
        _harvest(nullAddress);
    }

    // compounds earnings and charges performance fee
    function _harvest(address callFeeRecipient) internal whenNotPaused {
        IMiniChefV2(chef).harvest(poolId, address(this));
        uint256 outputBal = IERC20(output).balanceOf(address(this));
        uint256 rewardBal = IERC20(reward).balanceOf(address(this));
        if (outputBal > 0 || rewardBal > 0) {
            chargeFees(callFeeRecipient);
            addLiquidity();
            deposit();
            lastHarvest = block.timestamp;
            emit StratHarvest(msg.sender);
        }
    }

    // performance fees
    function chargeFees(address callFeeRecipient) internal {
        // v2 harvester rewards are in both output and reward, convert reward to output
        uint256 toOutput = IERC20(reward).balanceOf(address(this));
        if (toOutput > 0) {
            IUniswapRouterETH(unirouter).swapExactTokensForTokens(toOutput, 0, rewardToOutputRoute, address(this), block.timestamp);
        }

        uint256 toNative = IERC20(output).balanceOf(address(this)).mul(45).div(1000);
        IUniswapRouterETH(unirouter).swapExactTokensForTokens(toNative, 0, outputToNativeRoute, address(this), block.timestamp);

        uint256 nativeBal = IERC20(native).balanceOf(address(this));

        uint256 callFeeAmount = nativeBal.mul(callFee).div(MAX_FEE);
        if (callFeeRecipient != nullAddress) {
            IERC20(native).safeTransfer(callFeeRecipient, callFeeAmount);
        } else {
            IERC20(native).safeTransfer(tx.origin, callFeeAmount);
        }

        uint256 beefyFeeAmount = nativeBal.mul(beefyFee).div(MAX_FEE);
        IERC20(native).safeTransfer(beefyFeeRecipient, beefyFeeAmount);

        uint256 strategistFee = nativeBal.mul(STRATEGIST_FEE).div(MAX_FEE);
        IERC20(native).safeTransfer(strategist, strategistFee);
    }

    // Adds liquidity to AMM and gets more LP tokens.
    function addLiquidity() internal {
        uint256 outputHalf = IERC20(output).balanceOf(address(this)).div(2);

        if (lpToken0 != output) {
            IUniswapRouterETH(unirouter).swapExactTokensForTokens(outputHalf, 0, outputToLp0Route, address(this), block.timestamp);
        }

        if (lpToken1 != output) {
            IUniswapRouterETH(unirouter).swapExactTokensForTokens(outputHalf, 0, outputToLp1Route, address(this), block.timestamp);
        }

        uint256 lp0Bal = IERC20(lpToken0).balanceOf(address(this));
        uint256 lp1Bal = IERC20(lpToken1).balanceOf(address(this));
        IUniswapRouterETH(unirouter).addLiquidity(lpToken0, lpToken1, lp0Bal, lp1Bal, 1, 1, address(this), block.timestamp);
    }

    // calculate the total underlaying 'want' held by the strat.
    function balanceOf() public view returns (uint256) {
        return balanceOfWant().add(balanceOfPool());
    }

    // it calculates how much 'want' this contract holds.
    function balanceOfWant() public view returns (uint256) {
        return IERC20(want).balanceOf(address(this));
    }

    // it calculates how much 'want' the strategy has working in the farm.
    function balanceOfPool() public view returns (uint256) {
        (uint256 _amount, ) = IMiniChefV2(chef).userInfo(poolId, address(this));
        return _amount;
    }

    // called as part of strat migration. Sends all the available funds back to the vault.
    function retireStrat() external {
        require(msg.sender == vault, "!vault");

        IMiniChefV2(chef).emergencyWithdraw(poolId, address(this));

        uint256 wantBal = IERC20(want).balanceOf(address(this));
        IERC20(want).transfer(vault, wantBal);
    }

    // returns rewards unharvested
    function rewardsAvailable() public view returns (uint256) {
        return IMiniChefV2(chef).pendingSushi(poolId, address(this));
    }

    // native reward amount for calling harvest
    function callReward() public view returns (uint256) {
        uint256 outputBal = rewardsAvailable();
        uint256 nativeOut;
         if (outputBal > 0) {
            try IUniswapRouterETH(unirouter).getAmountsOut(outputBal, outputToNativeRoute)
                returns (uint256[] memory amountOut) 
            {
                nativeOut = amountOut[amountOut.length -1];
            }
            catch {}
        }

        uint256 pendingNative;
        address rewarder = IMiniChefV2(chef).rewarder(poolId);
        if (rewarder != nullAddress) {
            pendingNative = IRewarder(rewarder).pendingToken(poolId, address(this));
        } 

        return pendingNative.add(nativeOut).mul(45).div(1000).mul(callFee).div(MAX_FEE);
    }

    function setHarvestOnDeposit(bool _harvestOnDeposit) external onlyManager {
        harvestOnDeposit = _harvestOnDeposit;

        if (harvestOnDeposit) {
            setWithdrawalFee(0);
        } else {
            setWithdrawalFee(10);
        }
    }

    // pauses deposits and withdraws all funds from third party systems.
    function panic() public onlyManager {
        pause();
        IMiniChefV2(chef).emergencyWithdraw(poolId, address(this));
    }

    function pause() public onlyManager {
        _pause();

        _removeAllowances();
    }

    function unpause() external onlyManager {
        _unpause();

        _giveAllowances();

        deposit();
    }

    function _giveAllowances() internal {
        IERC20(want).safeApprove(chef, type(uint256).max);
        IERC20(output).safeApprove(unirouter, type(uint256).max);
        IERC20(reward).safeApprove(unirouter, type(uint256).max);

        IERC20(lpToken0).safeApprove(unirouter, 0);
        IERC20(lpToken0).safeApprove(unirouter, type(uint256).max);

        IERC20(lpToken1).safeApprove(unirouter, 0);
        IERC20(lpToken1).safeApprove(unirouter, type(uint256).max);
    }

    function _removeAllowances() internal {
        IERC20(want).safeApprove(chef, 0);
        IERC20(output).safeApprove(unirouter, 0);
        IERC20(reward).safeApprove(unirouter, 0);
        IERC20(lpToken0).safeApprove(unirouter, 0);
        IERC20(lpToken1).safeApprove(unirouter, 0);
    }
}