function addDays(date, dayAdd) {
	millisec = dayAdd * 86400000;
	newTime = date.getTime() + millisec;
	return new Date(newTime);
}
function diffDays(date1, date2) {
	diff = Math.round((date2.getTime() - date1.getTime())/86400000  );
	return diff;
}
		
function setNumberNight() {
  var date_ini_str = document.getElementById('date_ini').value;
  var date_end_str = document.getElementById('date_end').value;
  var date_ini=date_ini_str.split("-");
  var date_end=date_end_str.split("-");
	var dataStart = new Date(date_ini[0],date_ini[1]-1,date_ini[2],12);
	var dataEnd = new Date(date_end[0],date_end[1]-1,date_end[2],12);

	if (dataStart<dataEnd) {
		document.getElementById('nights_').value=diffDays(dataStart, dataEnd);
		document.getElementById('notti_').value=diffDays(dataStart, dataEnd);
	} else {
	 	document.getElementById('nights_').value=3;
	 	document.getElementById('notti_').value=3;
		dataEnd =  new Date();
		dataEnd = addDays (dataStart, Number(document.getElementById('nights_').value));
		var d  = dataEnd.getDate();
    var day = (d < 10) ? '0' + d : d;
    var m = dataEnd.getMonth() + 1;
    var month = (m < 10) ? '0' + m : m;

		document.getElementById('date_end').value = dataEnd.getFullYear()+"-"+month+"-"+day;
	}
	return true;
}