var shown = '0';
  
  function hideMenu(i)
  {
   document.getElementById("div"+i).style.display="none";
  }
  
  function showMenu(i)
  {   

   document.getElementById("div"+i).style.display="inline";
   if ((shown!='0') && (shown!=i))
   {
    hideMenu(shown);
   }
   shown=i;
  }