var selectedOptions = [];
function countSelected(select, maxNumber)
{
	for(var i = 0; i < select.options.length; i++)
	{
		if(select.options[i].selected && !new RegExp(i, 'g').test(selectedOptions.toString()))
		{
			if( select.options[i].value != '' )
				selectedOptions.push(i);
			else
				selectedOptions.pop();
		}

		if(!select.options[i].selected && new RegExp(i, 'g').test(selectedOptions.toString()))
		{
			selectedOptions = selectedOptions.sort(function(a, b){return a - b});  
			for(var j = 0; j < selectedOptions.length; j++)
			{
				if(selectedOptions[j] == i)
				{
					selectedOptions.splice(j, 1);
				}
			}
		}

		if(selectedOptions.length > maxNumber)
		{
			var throwAlert = true;
			select.options[i].selected = false;
			selectedOptions.pop();
		}  
	}            

	if(throwAlert == true)
	{
		alert('You may only choose ' + maxNumber + ' options!');
		document.body.focus();
	}
}