var backgroundNumber = 1;
var bgTimer = null;
var clockTimer = null;
function flipImage(number) {
	if(number <= 4) {
		backgroundNumber = number;
		if(document.all) {	
			document.getElementById('main-image').filters[0].apply(); 
		}
		document.getElementById('main-image').src = 'images/banners/main_'+backgroundNumber+'.jpg';
		if(document.all) {			
			document.getElementById('main-image').filters[0].play(3);
		}
		// cache next image
		var nextImage = (backgroundNumber+1);
		//alert(nextImage);
		objImage = new Image();
		objImage.src='images/banners/main_'+nextImage+'.jpg';
		//
		setTimeout("flipImage("+nextImage+");", 6000);
	}
	else {
		number = Math.floor(Math.random()*1)+1;
		if(number>1) {
			number = Math.floor(Math.random()*3)+2;
		}
		setTimeout("flipImage("+number+");", 1000);
	}
}


function contact_link(id) {   
	var username = "info";
	var hostname = "360-edu.com";
	document.getElementById(id).innerHTML = '<' + 'a href="' + 'mail' + 'to:' + username + '@' + hostname + '">' + username +'@' + hostname  + '<' + '/a' + '>';
}


function isNumberKey(evt) {
	var charCode = (evt.which) ? evt.which : event.keyCode
	if (charCode > 31 && (charCode < 48 || charCode > 57))
	return false;
	
	return true;
}