function addDays(newDate, dayAdd) {
	millisec = (dayAdd) * 86400000;
	newTime = newDate.getTime() + millisec;
	return new Date(newTime);
}

function setEndNight() {
	if (!isNaN(Number (document.getElementById('nights').value)) ){
		var dataEnd =  new Date();
		var sDayVal  = Number(document.getElementById('arr_date')[document.getElementById('arr_date').selectedIndex].value);
		var sMonthVal= Number(document.getElementById('arr_mon')[document.getElementById('arr_mon').selectedIndex].value);
		var sYearVal = Number(document.getElementById('arr_year')[document.getElementById('arr_year').selectedIndex].value);
		var dataStart = new Date(sYearVal,sMonthVal-1,sDayVal,12,00,00);

		dataEnd = addDays(dataStart, Number(document.getElementById('nights').value));
//		dataEnd.setDate(dataStart.getDate() + Number(document.getElementById('nights').value));
//		alert(dataStart+" - "+dataEnd);

		document.getElementById('dep_date').value=dataEnd.getDate();
		document.getElementById('dep_mon').value=dataEnd.getMonth()+1;
		document.getElementById('dep_year').value=dataEnd.getFullYear();

	} else {
			document.getElementById('nights').value="0";
			alert ("Invalid Night number");
		}
	return true;
}