pragma solidity ^0.4.21;

contract  IYFIO {
   
    uint256 public totalSupply;

 
    function balanceOf(address _owner) public view returns (uint256 balance);


    function transfer(address _to, uint256 _value) public returns (bool success);


    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);


    function approve(address _spender, uint256 _value) public returns (bool success);


    function allowance(address _owner, address _spender) public view returns (uint256 remaining);


    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

library SafeMath {

  
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {

    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }


  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); 
    uint256 c = a / b;


    return c;
  }



  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }


  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }


  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}


contract YFIO is IYFIO {
    using SafeMath for uint256;

    mapping (address => uint256) public balances;
    mapping (address => mapping (address => uint256)) public allowed;

    string public name;                   
    uint8 public decimals;                
    string public symbol;                 

    function YFIO(
        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;
    }

    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;
    }

    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }

    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;
    }

    function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
        require(_spender != address(0));
        return allowed[_owner][_spender];
    }
}