function displaydivTop(divid) {
var divs=['11', '12', '13', '14', '15', '16'];
var onediv = document.getElementById(divid);
for (var di=0;di<divs.length;di++)
  {
  if (onediv != document.getElementById(divs[di]))
    {
    document.getElementById(divs[di]).style.display='none';
    }
  }
onediv.style.display = 'block';
}
function displaydivBottom(divid) {
var divs=['21', '22', '23', '24', '25', '26', '27'];
var onediv = document.getElementById(divid);
for (var di=0;di<divs.length;di++)
  {
  if (onediv != document.getElementById(divs[di]))
    {
    document.getElementById(divs[di]).style.display='none';
    }
  }
onediv.style.display = 'block';
}