library SafeMath {
	function mul(uint256 a, uint256 b) internal constant returns (uint256) {
		uint256 c = a * b;
		assert(a == 0 || c / a == b);
		return c;
	}

	/* function div(uint256 a, uint256 b) internal constant returns (uint256) {
		// assert(b > 0); // Solidity automatically throws when dividing by 0
		uint256 c = a / b;
		// assert(a == b * c + a % b); // There is no case in which this doesn't hold
		return c;
	} */

	function sub(uint256 a, uint256 b) internal constant returns (uint256) {
		assert(b <= a);
		return a - b;
	}

	function add(uint256 a, uint256 b) internal constant returns (uint256) {
		uint256 c = a + b;
		assert(c >= a);
		return c;
	}
}
/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
function sub(uint256 a, uint256 b) internal constant returns (uint256) {
	assert(b <= a);
	return a - b;
}

/* function div(uint256 a, uint256 b) internal constant returns (uint256) {
 		// assert(b > 0); // Solidity automatically throws when dividing by 0
 		uint256 c = a / b;
 		// assert(a == b * c + a % b); // There is no case in which this doesn't hold
 		return c;
 	} */