function changeCal(cal1, cal2, i1, i2) {
	document.getElementById(cal1).style.display = "block";
	document.getElementById(cal1).style.visibility = "visible";
	document.getElementById(cal1).style.zIndex = 2;
	document.getElementById(i1).className = "year";
	document.getElementById(cal2).style.zIndex = 1;
	document.getElementById(cal2).style.display = "none";
	document.getElementById(cal2).style.visibility = "hidden";
	document.getElementById(i2).className = '';
}