// File: contracts/ConnectCrowdsale.sol



pragma solidity >=0.5.0 <0.7.0;

import { Crowdsale } from "ozcontracts250/crowdsale/Crowdsale.sol";
import { AllowanceCrowdsale } from "ozcontracts250/crowdsale/emission/AllowanceCrowdsale.sol";
import { TimedCrowdsale } from "ozcontracts250/crowdsale/validation/TimedCrowdsale.sol";
import { IERC20 } from "ozcontracts250/token/ERC20/IERC20.sol";
import { IIndexedUniswapV2Oracle } from "./IIndexedUniswapV2Oracle.sol";

contract ConnectCrowdsale is Crowdsale, AllowanceCrowdsale, TimedCrowdsale {
  address public oracle;
  address constant USDC_ADDRESS = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
  constructor(
    address payable wallet,
    IERC20 token,
    uint256 openingTime,
    uint256 closingTime,
    address _oracle
  ) public AllowanceCrowdsale(wallet) TimedCrowdsale(openingTime, closingTime) Crowdsale(1, wallet, token) {
    oracle = _oracle;
  }
  function updatePrice() internal {
    IIndexedUniswapV2Oracle(oracle).updatePrice(USDC_ADDRESS);
  }
  function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
    return weiAmount.mul(rate());
  }
  function rate() public view returns (uint256) {
    return uint256(1 ether).div(uint256(IIndexedUniswapV2Oracle(oracle).computeAverageEthForTokens(USDC_ADDRESS, 1e5, 0, 60*60*24*2))); // take two day moving average
  }
  function() external payable {
    updatePrice();
    buyTokens(_msgSender());
  }
}

// File: ozcontracts250/crowdsale/Crowdsale.sol



pragma solidity ^0.5.0;

import "../GSN/Context.sol";
import "../token/ERC20/IERC20.sol";
import "../math/SafeMath.sol";
import "../token/ERC20/SafeERC20.sol";
import "../utils/ReentrancyGuard.sol";

/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale,
 * allowing investors to purchase tokens with ether. This contract implements
 * such functionality in its most fundamental form and can be extended to provide additional
 * functionality and/or custom behavior.
 * The external interface represents the basic interface for purchasing tokens, and conforms
 * the base architecture for crowdsales. It is *not* intended to be modified / overridden.
 * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
 * the methods to add functionality. Consider using 'super' where appropriate to concatenate
 * behavior.
 */
contract Crowdsale is Context, ReentrancyGuard {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // The token being sold
    IERC20 private _token;

    // Address where funds are collected
    address payable private _wallet;

    // How many token units a buyer gets per wei.
    // The rate is the conversion between wei and the smallest and indivisible token unit.
    // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
    // 1 wei will give you 1 unit, or 0.001 TOK.
    uint256 private _rate;

    // Amount of wei raised
    uint256 private _weiRaised;

    /**
     * Event for token purchase logging
     * @param purchaser who paid for the tokens
     * @param beneficiary who got the tokens
     * @param value weis paid for purchase
     * @param amount amount of tokens purchased
     */
    event TokensPurchased(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

    /**
     * @param rate Number of token units a buyer gets per wei
     * @dev The rate is the conversion between wei and the smallest and indivisible
     * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
     * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
     * @param wallet Address where collected funds will be forwarded to
     * @param token Address of the token being sold
     */
    constructor (uint256 rate, address payable wallet, IERC20 token) public {
        require(rate > 0, "Crowdsale: rate is 0");
        require(wallet != address(0), "Crowdsale: wallet is the zero address");
        require(address(token) != address(0), "Crowdsale: token is the zero address");

        _rate = rate;
        _wallet = wallet;
        _token = token;
    }

    /**
     * @dev fallback function ***DO NOT OVERRIDE***
     * Note that other contracts will transfer funds with a base gas stipend
     * of 2300, which is not enough to call buyTokens. Consider calling
     * buyTokens directly when purchasing tokens from a contract.
     */
    function () external payable {
        buyTokens(_msgSender());
    }

    /**
     * @return the token being sold.
     */
    function token() public view returns (IERC20) {
        return _token;
    }

    /**
     * @return the address where funds are collected.
     */
    function wallet() public view returns (address payable) {
        return _wallet;
    }

    /**
     * @return the number of token units a buyer gets per wei.
     */
    function rate() public view returns (uint256) {
        return _rate;
    }

    /**
     * @return the amount of wei raised.
     */
    function weiRaised() public view returns (uint256) {
        return _weiRaised;
    }

    /**
     * @dev low level token purchase ***DO NOT OVERRIDE***
     * This function has a non-reentrancy guard, so it shouldn't be called by
     * another `nonReentrant` function.
     * @param beneficiary Recipient of the token purchase
     */
    function buyTokens(address beneficiary) public nonReentrant payable {
        uint256 weiAmount = msg.value;
        _preValidatePurchase(beneficiary, weiAmount);

        // calculate token amount to be created
        uint256 tokens = _getTokenAmount(weiAmount);

        // update state
        _weiRaised = _weiRaised.add(weiAmount);

        _processPurchase(beneficiary, tokens);
        emit TokensPurchased(_msgSender(), beneficiary, weiAmount, tokens);

        _updatePurchasingState(beneficiary, weiAmount);

        _forwardFunds();
        _postValidatePurchase(beneficiary, weiAmount);
    }

    /**
     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
     * Use `super` in contracts that inherit from Crowdsale to extend their validations.
     * Example from CappedCrowdsale.sol's _preValidatePurchase method:
     *     super._preValidatePurchase(beneficiary, weiAmount);
     *     require(weiRaised().add(weiAmount) <= cap);
     * @param beneficiary Address performing the token purchase
     * @param weiAmount Value in wei involved in the purchase
     */
    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        require(beneficiary != address(0), "Crowdsale: beneficiary is the zero address");
        require(weiAmount != 0, "Crowdsale: weiAmount is 0");
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
    }

    /**
     * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid
     * conditions are not met.
     * @param beneficiary Address performing the token purchase
     * @param weiAmount Value in wei involved in the purchase
     */
    function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends
     * its tokens.
     * @param beneficiary Address performing the token purchase
     * @param tokenAmount Number of tokens to be emitted
     */
    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
        _token.safeTransfer(beneficiary, tokenAmount);
    }

    /**
     * @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send
     * tokens.
     * @param beneficiary Address receiving the tokens
     * @param tokenAmount Number of tokens to be purchased
     */
    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
        _deliverTokens(beneficiary, tokenAmount);
    }

    /**
     * @dev Override for extensions that require an internal state to check for validity (current user contributions,
     * etc.)
     * @param beneficiary Address receiving the tokens
     * @param weiAmount Value in wei involved in the purchase
     */
    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @dev Override to extend the way in which ether is converted to tokens.
     * @param weiAmount Value in wei to be converted into tokens
     * @return Number of tokens that can be purchased with the specified _weiAmount
     */
    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
        return weiAmount.mul(_rate);
    }

    /**
     * @dev Determines how ETH is stored/forwarded on purchases.
     */
    function _forwardFunds() internal {
        _wallet.transfer(msg.value);
    }
}

// File: ozcontracts250/crowdsale/emission/AllowanceCrowdsale.sol



pragma solidity ^0.5.0;

import "../Crowdsale.sol";
import "../../token/ERC20/IERC20.sol";
import "../../token/ERC20/SafeERC20.sol";
import "../../math/SafeMath.sol";
import "../../math/Math.sol";

/**
 * @title AllowanceCrowdsale
 * @dev Extension of Crowdsale where tokens are held by a wallet, which approves an allowance to the crowdsale.
 */
contract AllowanceCrowdsale is Crowdsale {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    address private _tokenWallet;

    /**
     * @dev Constructor, takes token wallet address.
     * @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale.
     */
    constructor (address tokenWallet) public {
        require(tokenWallet != address(0), "AllowanceCrowdsale: token wallet is the zero address");
        _tokenWallet = tokenWallet;
    }

    /**
     * @return the address of the wallet that will hold the tokens.
     */
    function tokenWallet() public view returns (address) {
        return _tokenWallet;
    }

    /**
     * @dev Checks the amount of tokens left in the allowance.
     * @return Amount of tokens left in the allowance
     */
    function remainingTokens() public view returns (uint256) {
        return Math.min(token().balanceOf(_tokenWallet), token().allowance(_tokenWallet, address(this)));
    }

    /**
     * @dev Overrides parent behavior by transferring tokens from wallet.
     * @param beneficiary Token purchaser
     * @param tokenAmount Amount of tokens purchased
     */
    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
        token().safeTransferFrom(_tokenWallet, beneficiary, tokenAmount);
    }
}

// File: ozcontracts250/crowdsale/validation/TimedCrowdsale.sol



pragma solidity ^0.5.0;

import "../../math/SafeMath.sol";
import "../Crowdsale.sol";

/**
 * @title TimedCrowdsale
 * @dev Crowdsale accepting contributions only within a time frame.
 */
contract TimedCrowdsale is Crowdsale {
    using SafeMath for uint256;

    uint256 private _openingTime;
    uint256 private _closingTime;

    /**
     * Event for crowdsale extending
     * @param newClosingTime new closing time
     * @param prevClosingTime old closing time
     */
    event TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime);

    /**
     * @dev Reverts if not in crowdsale time range.
     */
    modifier onlyWhileOpen {
        require(isOpen(), "TimedCrowdsale: not open");
        _;
    }

    /**
     * @dev Constructor, takes crowdsale opening and closing times.
     * @param openingTime Crowdsale opening time
     * @param closingTime Crowdsale closing time
     */
    constructor (uint256 openingTime, uint256 closingTime) public {
        // solhint-disable-next-line not-rely-on-time
        require(openingTime >= block.timestamp, "TimedCrowdsale: opening time is before current time");
        // solhint-disable-next-line max-line-length
        require(closingTime > openingTime, "TimedCrowdsale: opening time is not before closing time");

        _openingTime = openingTime;
        _closingTime = closingTime;
    }

    /**
     * @return the crowdsale opening time.
     */
    function openingTime() public view returns (uint256) {
        return _openingTime;
    }

    /**
     * @return the crowdsale closing time.
     */
    function closingTime() public view returns (uint256) {
        return _closingTime;
    }

    /**
     * @return true if the crowdsale is open, false otherwise.
     */
    function isOpen() public view returns (bool) {
        // solhint-disable-next-line not-rely-on-time
        return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
    }

    /**
     * @dev Checks whether the period in which the crowdsale is open has already elapsed.
     * @return Whether crowdsale period has elapsed
     */
    function hasClosed() public view returns (bool) {
        // solhint-disable-next-line not-rely-on-time
        return block.timestamp > _closingTime;
    }

    /**
     * @dev Extend parent behavior requiring to be within contributing period.
     * @param beneficiary Token purchaser
     * @param weiAmount Amount of wei contributed
     */
    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal onlyWhileOpen view {
        super._preValidatePurchase(beneficiary, weiAmount);
    }

    /**
     * @dev Extend crowdsale.
     * @param newClosingTime Crowdsale closing time
     */
    function _extendTime(uint256 newClosingTime) internal {
        require(!hasClosed(), "TimedCrowdsale: already closed");
        // solhint-disable-next-line max-line-length
        require(newClosingTime > _closingTime, "TimedCrowdsale: new closing time is before current closing time");

        emit TimedCrowdsaleExtended(_closingTime, newClosingTime);
        _closingTime = newClosingTime;
    }
}

// File: ozcontracts250/token/ERC20/IERC20.sol



pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
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: contracts/IIndexedUniswapV2Oracle.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.5.0;
pragma experimental ABIEncoderV2;

/* ==========  Libraries  ========== */
import "./PriceLibrary.sol";
import "./FixedPoint.sol";


interface IIndexedUniswapV2Oracle {
/* ==========  Mutative Functions  ========== */

  function updatePrice(address token) external returns (bool);

  function updatePrices(address[] calldata tokens) external returns (bool[] memory);

/* ==========  Meta Price Queries  ========== */

  function hasPriceObservationInWindow(address token, uint256 priceKey) external view returns (bool);

  function getPriceObservationInWindow(
    address token, uint256 priceKey
  ) external view returns (PriceLibrary.PriceObservation memory);

  function getPriceObservationsInRange(
    address token, uint256 timeFrom, uint256 timeTo
  ) external view returns (PriceLibrary.PriceObservation[] memory prices);

/* ==========  Price Update Queries  ========== */

  function canUpdatePrice(address token) external view returns (bool);

  function canUpdatePrices(address[] calldata tokens) external view returns (bool[] memory);

/* ==========  Price Queries: Singular  ========== */

  function computeTwoWayAveragePrice(
    address token, uint256 minTimeElapsed, uint256 maxTimeElapsed
  ) external view returns (PriceLibrary.TwoWayAveragePrice memory);

  function computeAverageTokenPrice(
    address token, uint256 minTimeElapsed, uint256 maxTimeElapsed
  ) external view returns (FixedPoint.uq112x112 memory);

  function computeAverageEthPrice(
    address token, uint256 minTimeElapsed, uint256 maxTimeElapsed
  ) external view returns (FixedPoint.uq112x112 memory);

/* ==========  Price Queries: Multiple  ========== */

  function computeTwoWayAveragePrices(
    address[] calldata tokens,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (PriceLibrary.TwoWayAveragePrice[] memory);

  function computeAverageTokenPrices(
    address[] calldata tokens,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (FixedPoint.uq112x112[] memory);

  function computeAverageEthPrices(
    address[] calldata tokens,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (FixedPoint.uq112x112[] memory);

/* ==========  Value Queries: Singular  ========== */

  function computeAverageEthForTokens(
    address token,
    uint256 tokenAmount,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (uint144);

  function computeAverageTokensForEth(
    address token,
    uint256 wethAmount,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (uint144);

/* ==========  Value Queries: Multiple  ========== */

  function computeAverageEthForTokens(
    address[] calldata tokens,
    uint256[] calldata tokenAmounts,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (uint144[] memory);

  function computeAverageTokensForEth(
    address[] calldata tokens,
    uint256[] calldata wethAmounts,
    uint256 minTimeElapsed,
    uint256 maxTimeElapsed
  ) external view returns (uint144[] memory);
}

// File: ozcontracts250/GSN/Context.sol



pragma solidity ^0.5.0;

/*
 * @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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

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

// File: ozcontracts250/math/SafeMath.sol



pragma solidity ^0.5.0;

/**
 * @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, 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) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: ozcontracts250/token/ERC20/SafeERC20.sol



pragma solidity ^0.5.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @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 ERC20;` 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));
    }

    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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "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: ozcontracts250/utils/ReentrancyGuard.sol



pragma solidity ^0.5.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 *
 * _Since v2.5.0:_ this module is now much more gas efficient, given net gas
 * metering changes introduced in the Istanbul hardfork.
 */
contract ReentrancyGuard {
    bool private _notEntered;

    constructor () internal {
        // Storing an initial non-zero value makes deployment a bit more
        // expensive, but in exchange the refund on every call to nonReentrant
        // will be lower in amount. Since refunds are capped to a percetange of
        // the total transaction's gas, it is best to keep them low in cases
        // like this one, to increase the likelihood of the full refund coming
        // into effect.
        _notEntered = true;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_notEntered, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _notEntered = false;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _notEntered = true;
    }
}

// File: ozcontracts250/utils/Address.sol



pragma solidity ^0.5.5;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

// File: ozcontracts250/math/Math.sol



pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// File: contracts/PriceLibrary.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.5.0;
pragma experimental ABIEncoderV2;

/* ==========  Internal Libraries  ========== */
import "./FixedPoint.sol";
import "./UniswapV2OracleLibrary.sol";
import "./UniswapV2Library.sol";


library PriceLibrary {
  using FixedPoint for FixedPoint.uq112x112;
  using FixedPoint for FixedPoint.uq144x112;

/* ========= Structs ========= */

  struct PriceObservation {
    uint32 timestamp;
    uint224 priceCumulativeLast;
    uint224 ethPriceCumulativeLast;
  }

  /**
   * @dev Average prices for a token in terms of weth and weth in terms of the token.
   *
   * Note: The average weth price is not equivalent to the reciprocal of the average
   * token price. See the UniSwap whitepaper for more info.
   */
  struct TwoWayAveragePrice {
    uint224 priceAverage;
    uint224 ethPriceAverage;
  }

/* ========= View Functions ========= */

  function pairInitialized(
    address uniswapFactory,
    address token,
    address weth
  )
    internal
    view
    returns (bool)
  {
    address pair = UniswapV2Library.pairFor(uniswapFactory, token, weth);
    (uint112 reserve0, uint112 reserve1,) = IUniswapV2Pair(pair).getReserves();
    return reserve0 != 0 && reserve1 != 0;
  }

  function observePrice(
    address uniswapFactory,
    address tokenIn,
    address quoteToken
  )
    internal
    view
    returns (uint32 /* timestamp */, uint224 /* priceCumulativeLast */)
  {
    (address token0, address token1) = UniswapV2Library.sortTokens(tokenIn, quoteToken);
    address pair = UniswapV2Library.calculatePair(uniswapFactory, token0, token1);
    if (token0 == tokenIn) {
      (uint256 price0Cumulative, uint32 blockTimestamp) = UniswapV2OracleLibrary.currentCumulativePrice0(pair);
      return (blockTimestamp, uint224(price0Cumulative));
    } else {
      (uint256 price1Cumulative, uint32 blockTimestamp) = UniswapV2OracleLibrary.currentCumulativePrice1(pair);
      return (blockTimestamp, uint224(price1Cumulative));
    }
  }

  /**
   * @dev Query the current cumulative price of a token in terms of weth
   * and the current cumulative price of weth in terms of the token.
   */
  function observeTwoWayPrice(
    address uniswapFactory,
    address token,
    address weth
  ) internal view returns (PriceObservation memory) {
    (address token0, address token1) = UniswapV2Library.sortTokens(token, weth);
    address pair = UniswapV2Library.calculatePair(uniswapFactory, token0, token1);
    // Get the sorted token prices
    (
      uint256 price0Cumulative,
      uint256 price1Cumulative,
      uint32 blockTimestamp
    ) = UniswapV2OracleLibrary.currentCumulativePrices(pair);
    // Check which token is weth and which is the token,
    // then build the price observation.
    if (token0 == token) {
      return PriceObservation({
        timestamp: blockTimestamp,
        priceCumulativeLast: uint224(price0Cumulative),
        ethPriceCumulativeLast: uint224(price1Cumulative)
      });
    } else {
      return PriceObservation({
        timestamp: blockTimestamp,
        priceCumulativeLast: uint224(price1Cumulative),
        ethPriceCumulativeLast: uint224(price0Cumulative)
      });
    }
  }

/* ========= Utility Functions ========= */

  /**
   * @dev Computes the average price of a token in terms of weth
   * and the average price of weth in terms of a token using two
   * price observations.
   */
  function computeTwoWayAveragePrice(
    PriceObservation memory observation1,
    PriceObservation memory observation2
  ) internal pure returns (TwoWayAveragePrice memory) {
    uint32 timeElapsed = uint32(observation2.timestamp - observation1.timestamp);
    FixedPoint.uq112x112 memory priceAverage = UniswapV2OracleLibrary.computeAveragePrice(
      observation1.priceCumulativeLast,
      observation2.priceCumulativeLast,
      timeElapsed
    );
    FixedPoint.uq112x112 memory ethPriceAverage = UniswapV2OracleLibrary.computeAveragePrice(
      observation1.ethPriceCumulativeLast,
      observation2.ethPriceCumulativeLast,
      timeElapsed
    );
    return TwoWayAveragePrice({
      priceAverage: priceAverage._x,
      ethPriceAverage: ethPriceAverage._x
    });
  }

  function computeAveragePrice(
    uint32 timestampStart,
    uint224 priceCumulativeStart,
    uint32 timestampEnd,
    uint224 priceCumulativeEnd
  ) internal pure returns (FixedPoint.uq112x112 memory) {
    return UniswapV2OracleLibrary.computeAveragePrice(
      priceCumulativeStart,
      priceCumulativeEnd,
      uint32(timestampEnd - timestampStart)
    );
  }

  /**
   * @dev Computes the average price of the token the price observations
   * are for in terms of weth.
   */
  function computeAverageTokenPrice(
    PriceObservation memory observation1,
    PriceObservation memory observation2
  ) internal pure returns (FixedPoint.uq112x112 memory) {
    return UniswapV2OracleLibrary.computeAveragePrice(
      observation1.priceCumulativeLast,
      observation2.priceCumulativeLast,
      uint32(observation2.timestamp - observation1.timestamp)
    );
  }

  /**
   * @dev Computes the average price of weth in terms of the token
   * the price observations are for.
   */
  function computeAverageEthPrice(
    PriceObservation memory observation1,
    PriceObservation memory observation2
  ) internal pure returns (FixedPoint.uq112x112 memory) {
    return UniswapV2OracleLibrary.computeAveragePrice(
      observation1.ethPriceCumulativeLast,
      observation2.ethPriceCumulativeLast,
      uint32(observation2.timestamp - observation1.timestamp)
    );
  }

  /**
   * @dev Compute the average value in weth of `tokenAmount` of the
   * token that the average price values are for.
   */
  function computeAverageEthForTokens(
    TwoWayAveragePrice memory prices,
    uint256 tokenAmount
  ) internal pure returns (uint144) {
    return FixedPoint.uq112x112(prices.priceAverage).mul(tokenAmount).decode144();
  }

  /**
   * @dev Compute the average value of `wethAmount` weth in terms of
   * the token that the average price values are for.
   */
  function computeAverageTokensForEth(
    TwoWayAveragePrice memory prices,
    uint256 wethAmount
  ) internal pure returns (uint144) {
    return FixedPoint.uq112x112(prices.ethPriceAverage).mul(wethAmount).decode144();
  }
}

// File: contracts/FixedPoint.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.5.0;


/************************************************************************************************
From https://github.com/Uniswap/uniswap-lib/blob/master/contracts/libraries/FixedPoint.sol

Copied from the github repository at commit hash 9642a0705fdaf36b477354a4167a8cd765250860.

Modifications:
- Removed `sqrt` function

Subject to the GPL-3.0 license
*************************************************************************************************/


// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
library FixedPoint {
  // range: [0, 2**112 - 1]
  // resolution: 1 / 2**112
  struct uq112x112 {
    uint224 _x;
  }

  // range: [0, 2**144 - 1]
  // resolution: 1 / 2**112
  struct uq144x112 {
    uint _x;
  }

  uint8 private constant RESOLUTION = 112;
  uint private constant Q112 = uint(1) << RESOLUTION;
  uint private constant Q224 = Q112 << RESOLUTION;

  // encode a uint112 as a UQ112x112
  function encode(uint112 x) internal pure returns (uq112x112 memory) {
    return uq112x112(uint224(x) << RESOLUTION);
  }

  // encodes a uint144 as a UQ144x112
  function encode144(uint144 x) internal pure returns (uq144x112 memory) {
    return uq144x112(uint256(x) << RESOLUTION);
  }

  // divide a UQ112x112 by a uint112, returning a UQ112x112
  function div(uq112x112 memory self, uint112 x) internal pure returns (uq112x112 memory) {
    require(x != 0, "FixedPoint: DIV_BY_ZERO");
    return uq112x112(self._x / uint224(x));
  }

  // multiply a UQ112x112 by a uint, returning a UQ144x112
  // reverts on overflow
  function mul(uq112x112 memory self, uint y) internal pure returns (uq144x112 memory) {
    uint z;
    require(
      y == 0 || (z = uint(self._x) * y) / y == uint(self._x),
      "FixedPoint: MULTIPLICATION_OVERFLOW"
    );
    return uq144x112(z);
  }

  // returns a UQ112x112 which represents the ratio of the numerator to the denominator
  // equivalent to encode(numerator).div(denominator)
  function fraction(uint112 numerator, uint112 denominator) internal pure returns (uq112x112 memory) {
    require(denominator > 0, "FixedPoint: DIV_BY_ZERO");
    return uq112x112((uint224(numerator) << RESOLUTION) / denominator);
  }

  // decode a UQ112x112 into a uint112 by truncating after the radix point
  function decode(uq112x112 memory self) internal pure returns (uint112) {
    return uint112(self._x >> RESOLUTION);
  }

  // decode a UQ144x112 into a uint144 by truncating after the radix point
  function decode144(uq144x112 memory self) internal pure returns (uint144) {
    return uint144(self._x >> RESOLUTION);
  }

  // take the reciprocal of a UQ112x112
  function reciprocal(uq112x112 memory self) internal pure returns (uq112x112 memory) {
    require(self._x != 0, "FixedPoint: ZERO_RECIPROCAL");
    return uq112x112(uint224(Q224 / self._x));
  }
}

// File: contracts/UniswapV2OracleLibrary.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.5.0;

/* ==========  Internal Interfaces  ========== */
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol";

/* ==========  Internal Libraries  ========== */
import "./FixedPoint.sol";


/************************************************************************************************
Originally from https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/libraries/UniswapV2OracleLibrary.sol

This source code has been modified from the original, which was copied from the github repository
at commit hash 6d03bede0a97c72323fa1c379ed3fdf7231d0b26.

Subject to the GPL-3.0 license
*************************************************************************************************/


// library with helper methods for oracles that are concerned with computing average prices
library UniswapV2OracleLibrary {
  using FixedPoint for *;

  // helper function that returns the current block timestamp within the range of uint32, i.e. [0, 2**32 - 1]
  function currentBlockTimestamp() internal view returns (uint32) {
    return uint32(block.timestamp % 2**32);
  }

  // produces the cumulative prices using counterfactuals to save gas and avoid a call to sync.
  function currentCumulativePrices(address pair)
    internal
    view
    returns (
      uint256 price0Cumulative,
      uint256 price1Cumulative,
      uint32 blockTimestamp
    )
  {
    blockTimestamp = currentBlockTimestamp();
    price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();
    price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

    // if time has elapsed since the last update on the pair, mock the accumulated price values
    (
      uint112 reserve0,
      uint112 reserve1,
      uint32 blockTimestampLast
    ) = IUniswapV2Pair(pair).getReserves();
    require(
      reserve0 != 0 && reserve1 != 0,
      "UniswapV2OracleLibrary::currentCumulativePrices: Pair has no reserves."
    );
    if (blockTimestampLast != blockTimestamp) {
      // subtraction overflow is desired
      uint32 timeElapsed = blockTimestamp - blockTimestampLast;
      // addition overflow is desired
      // counterfactual
      price0Cumulative += (
        uint256(FixedPoint.fraction(reserve1, reserve0)._x) *
        timeElapsed
      );
      // counterfactual
      price1Cumulative += (
        uint256(FixedPoint.fraction(reserve0, reserve1)._x) *
        timeElapsed
      );
    }
  }

  // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
  // only gets the first price
  function currentCumulativePrice0(address pair)
    internal
    view
    returns (uint256 price0Cumulative, uint32 blockTimestamp)
  {
    blockTimestamp = currentBlockTimestamp();
    price0Cumulative = IUniswapV2Pair(pair).price0CumulativeLast();

    // if time has elapsed since the last update on the pair, mock the accumulated price values
    (
      uint112 reserve0,
      uint112 reserve1,
      uint32 blockTimestampLast
    ) = IUniswapV2Pair(pair).getReserves();
    require(
      reserve0 != 0 && reserve1 != 0,
      "UniswapV2OracleLibrary::currentCumulativePrice0: Pair has no reserves."
    );
    if (blockTimestampLast != blockTimestamp) {
      // subtraction overflow is desired
      uint32 timeElapsed = blockTimestamp - blockTimestampLast;
      // addition overflow is desired
      // counterfactual
      price0Cumulative += (
        uint256(FixedPoint.fraction(reserve1, reserve0)._x) *
        timeElapsed
      );
    }
  }

  // produces the cumulative price using counterfactuals to save gas and avoid a call to sync.
  // only gets the second price
  function currentCumulativePrice1(address pair)
    internal
    view
    returns (uint256 price1Cumulative, uint32 blockTimestamp)
  {
    blockTimestamp = currentBlockTimestamp();
    price1Cumulative = IUniswapV2Pair(pair).price1CumulativeLast();

    // if time has elapsed since the last update on the pair, mock the accumulated price values
    (
      uint112 reserve0,
      uint112 reserve1,
      uint32 blockTimestampLast
    ) = IUniswapV2Pair(pair).getReserves();
    require(
      reserve0 != 0 && reserve1 != 0,
      "UniswapV2OracleLibrary::currentCumulativePrice1: Pair has no reserves."
    );
    if (blockTimestampLast != blockTimestamp) {
      // subtraction overflow is desired
      uint32 timeElapsed = blockTimestamp - blockTimestampLast;
      // addition overflow is desired
      // counterfactual
      price1Cumulative += (
        uint256(FixedPoint.fraction(reserve0, reserve1)._x) *
        timeElapsed
      );
    }
  }

  function computeAveragePrice(
    uint224 priceCumulativeStart,
    uint224 priceCumulativeEnd,
    uint32 timeElapsed
  ) internal pure returns (FixedPoint.uq112x112 memory priceAverage) {
    // overflow is desired.
    priceAverage = FixedPoint.uq112x112(
      uint224((priceCumulativeEnd - priceCumulativeStart) / timeElapsed)
    );
  }
}

// File: contracts/UniswapV2Library.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.5.0;

/************************************************************************************************
Originally from https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/libraries/UniswapV2Library.sol

This source code has been modified from the original, which was copied from the github repository
at commit hash 87edfdcaf49ccc52591502993db4c8c08ea9eec0.

Subject to the GPL-3.0 license
*************************************************************************************************/


library UniswapV2Library {
  // returns sorted token addresses, used to handle return values from pairs sorted in this order
  function sortTokens(address tokenA, address tokenB)
    internal
    pure
    returns (address token0, address token1)
  {
    require(tokenA != tokenB, "UniswapV2Library: IDENTICAL_ADDRESSES");
    (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
    require(token0 != address(0), "UniswapV2Library: ZERO_ADDRESS");
  }

  function calculatePair(
    address factory,
    address token0,
    address token1
  ) internal pure returns (address pair) {
    pair = address(
      uint256(
        keccak256(
          abi.encodePacked(
            hex"ff",
            factory,
            keccak256(abi.encodePacked(token0, token1)),
            hex"96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f" // init code hash
          )
        )
      )
    );
  }

  // calculates the CREATE2 address for a pair without making any external calls
  function pairFor(
    address factory,
    address tokenA,
    address tokenB
  ) internal pure returns (address pair) {
    (address token0, address token1) = sortTokens(tokenA, tokenB);
    pair = calculatePair(factory, token0, token1);
  }
}

// File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol



pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}