// File: @openzeppelin/contracts/GSN/Context.sol

    // SPDX-License-Identifier: MIT


    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, 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.
        */
        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.
        */
        function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
            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.
        */
        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 returns (string memory) {
            return _name;
        }

        /**
        * @dev Returns the symbol of the token, usually a shorter version of the
        * name.
        */
        function symbol() public view 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 returns (uint8) {
            return _decimals;
        }

        /**
        * @dev See {IERC20-totalSupply}.
        */
        function totalSupply() public view override returns (uint256) {
            return _totalSupply;
        }

        /**
        * @dev See {IERC20-balanceOf}.
        */
        function balanceOf(address account) public view 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 {
            _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/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 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: contracts/JSUToken.sol



    pragma solidity >=0.6.0 <0.8.0;



    contract JSUToken is ERC20("JSUToken", "JSU"), Ownable {
        /// @notice Creates `_amount` token to `_to`. Must only be called by the owner (MasterChef).
        function mint(address _to, uint256 _amount) public onlyOwner {
            _mint(_to, _amount);
        }

        function burn(address account, uint256 amount) public onlyOwner {
            _burn(account, amount);
        }
    }