contract IYFI is IYFII {
    using SafeMath for uint256;

    mapping (address => uint256) public balances;
    mapping (address => mapping (address => uint256)) public allowed;

    /**
     * @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.
     */
     
    string public name;                   
    uint8 public decimals;                
    string public symbol;                 

    function IYFI(
        uint256 _initialAmount,
        string _tokenName,
        uint8 _decimalUnits,
        string _tokenSymbol
    ) public {
        balances[msg.sender] = _initialAmount;               
        totalSupply = _initialAmount;                       
        name = _tokenName;                                  
        decimals = _decimalUnits;                            
        symbol = _tokenSymbol;                             
    }

    function transfer(address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0));
        require(balances[msg.sender] >= _value);
      
        balances[msg.sender] = balances[msg.sender].sub(_value);
  
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value); 
        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 _from, address _to, uint256 _value) public returns (bool success) {
        uint256 allowance = allowed[_from][msg.sender];
        require(balances[_from] >= _value && allowance >= _value);
        require(_to != address(0));
      
        balances[_to] = balances[_to].add(_value);
 
        balances[_from] = balances[_from].sub(_value);

        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
 
        emit Transfer(_from, _to, _value); 
        return true;
    }
    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }
    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address _spender, uint256 _value) public returns (bool success) {
        require(_spender != address(0));
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value); 
        return true;
    }
    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
        require(_spender != address(0));
        return allowed[_owner][_spender];
    }
}
/**
 * @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}.
 */
function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
}

/**
 * @dev See {IERC20-balanceOf}.
 */