function getElementsByClass(node,searchClass,tag) {
  var classElements = new Array();
  var els = document.getElementById('menu').getElementsByTagName(tag); // use "*" for all elements
  var elsLen = els.length;
  var pattern = new RegExp("\\b"+searchClass+"\\b");
  for (i = 0, j = 0; i < elsLen; i++) {
    if (pattern.test(els[i].className) ) {
      classElements[j] = els[i];
      j++;
    }
  }
  return classElements;
}

function unwrap(n) {
  var el = getElementsByClass(document,'third','ul');
  for(i = 0;i < el.length;i++)
    el[i].style.display = 'none';

  if(n != '*') el[n].style.display = 'block';

  return false;
}