function showMenu(divnum){
	clearMenu();
    	objdiv = 'subnav'+divnum;
	var obj = document.getElementById(objdiv);
     if(obj!=null){
        obj.style.display ='block';
     }
}

function hideMenu(divnum){
    	objdiv = 'subnav'+divnum;
	var obj = document.getElementById(objdiv);
     if(obj!=null){
        obj.style.display ='none';
     }
}

function clearMenu() {
    for(var i=1;i<6;i++){
        hideMenu(i);
    }
}