function calcRemaining(from, output)
	{
	var totalLength = 500;
	var messageString = document.getElementById(from).value;
	var currentLength = messageString.length;
	if(currentLength > 500)
		{
		alert('Message is too long.');
		document.getElementById(from).value = messageString.substr(0, 500);
		calcRemaining(from, output);
		}
	else
		{
		var remainingLength = 500 - currentLength;
		document.getElementById(output).innerHTML = remainingLength;	
		}
	}