function prepareMenu(){
	var cnt=0;
	var menu = document.getElementById("menu"); // ul main
	var li = menu.getElementsByTagName("li"); // li main

	// loop through all main lis
	for(x=0;x<li.length;x++){
		if(li[x].className=="li_main"){
			li[x].onmouseover=function(){
				displaySubLevel(this);
			}
			li[x].onmouseout=function(){
				hideSubLevel(this);
			}
		}
	}

	// loop through all 2nd level lis
	var ul_2nd = menu.getElementsByTagName("ul");
	for(y=0;y<ul_2nd.length;y++){
		if(ul_2nd[y].className=="ul_2nd"){
			var li_2nd = ul_2nd[y].getElementsByTagName("li");
			for(z=0;z<li_2nd.length;z++){
				//if(li_2nd[z].className=="li_2nd"){
				if(li_2nd[z].className.indexOf("li_2nd")>-1){
					cnt+=1;
					li_2nd[z].onmouseover=function(){
						displaySubLevel(this);
					}
					li_2nd[z].onmouseout=function(){
						hideSubLevel(this);
					}
				}
			}
		}
	}
}

function displaySubLevel(liObj){
	var li_main = document.getElementById(liObj.id);
	var ul_child = li_main.getElementsByTagName("ul")[0];
	//if(ul_child) alert("yes");
	if(ul_child) ul_child.style.display='block';
}

function hideSubLevel(liObj){
	var li_main = document.getElementById(liObj.id);
	var ul_child = li_main.getElementsByTagName("ul")[0];
	//alert(ul_child.nodeName);
	if(ul_child) ul_child.style.display='none';
}