contract StandardToken is ERC20, BasicToken
{
    //--------------------------------------------------------------------------
    //
    //	Properties
    //
    //--------------------------------------------------------------------------

    mapping (address => mapping (address => uint256)) internal allowed;

    //--------------------------------------------------------------------------
    //
    //	Public Methods
    //
    //--------------------------------------------------------------------------

    function transferFrom(address _from,address _to,uint256 _value) public returns (bool)
    {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender,uint256 _value) public returns (bool)
    {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner,address _spender) public view returns (uint256)
    {
        return allowed[_owner][_spender];
    }

    function increaseApproval(address _spender,uint _addedValue) public returns (bool)
    {
        allowed[msg.sender][_spender] = (allowed[msg.sender][_spender].add(_addedValue));
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    function decreaseApproval(address _spender,uint _subtractedValue) public returns (bool)
    {
        uint oldValue = allowed[msg.sender][_spender];
        if(_subtractedValue > oldValue)
        {
            allowed[msg.sender][_spender] = 0;
        }
        else
        {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }
}
function transferFrom(address _from,address _to,uint256 _value) public returns (bool)
{
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
}

//--------------------------------------------------------------------------
//
//	Public Methods
//
//--------------------------------------------------------------------------