function unPack(id) {
   var ul = document.getElementById(id);
   if (ul.style.display == 'none') {
				ul.style.display = 'block';
			} 
			else {
				ul.style.display = 'none';
			}
		}

function checkDateOfFinishYear(cntYears) {
	var start_month = document.getElementById("start_month");
	var start_year = document.getElementById("start_year");
	var date_finish = document.getElementById("date_finish");
	
	if(parseInt(start_month.value) == 1) {
		date_finish.innerText = " - prosinec " + ( parseInt(start_year.value) + parseInt(cntYears) - 1 );
	}
	else {
		var year = parseInt(start_year.value);
		year += parseInt(cntYears);
		var month;
		switch (parseInt(start_month.value)) {
			case 2:
				month = "leden";
				break;
			case 3:
				month = "únor";
				break;
			case 4:
				month = "březen";
				break;
			case 5:
				month = "duben";
				break;
			case 6:
				month = "květen";
				break;
			case 7:
				month = "červen";
				break;
			case 8:
				month = "červenec";
				break;
			case 9:
				month = "srpen";
				break;
			case 10:
				month = "září";
				break;
			case 11:
				month = "říjen";
				break;
			case 12:
				month = "listopad";
				break;
		}
		date_finish.innerText = " - " + month + " " + year; 
	}
}