function check_num_guests()
{
	var elem = document.getElementById("num_guests");
	
	if(elem.selectedIndex == elem.options.length-1)
	{
			document.getElementById("custom_guest_num").style.display = "inline";
			document.getElementById("custom_guest_num").value = "";
			document.getElementById("custom_guest_num").focus();
	}
	else
	{
		document.getElementById("custom_guest_num").style.display = "none";
	}
}

check_num_guests();