function displaySubMenu(li) 
{
    var subMenu = li.getElementsByTagName("ul")[0];
    subMenu.style.display = "block";
}
function hideSubMenu(li) 
{
    var subMenu = li.getElementsByTagName("ul")[0];
    subMenu.style.display = "none";
}

/*function displaySubMenu(id) 
{   
     
    document.getElementById(id).style.display="block";
}
function hideSubMenu(id) 
{
    document.getElementById(id).style.display ="none";    
}
*/