function menu(n)
{

  for (i=1; i<350; i++)
  {
    if (document.getElementById('menu'+i)) 
      {
        document.getElementById('menu'+i).style.visibility = 'hidden';
        document.getElementById('menu'+i).style.position = 'absolute';
      }
  }

  if (document.getElementById('menu'+n)) 
  {
    if (document.getElementById('menu'+n).className == 'visible')
    {
      document.getElementById('menu'+n).style.visibility = 'hidden';
      document.getElementById('menu'+n).style.position = 'absolute';
    }
    else
    {
      document.getElementById('menu'+n).style.visibility = 'visible';
      document.getElementById('menu'+n).style.position = 'static';
    }
  }

}