var totalCount = 0;
	  var maxCount = 4;
	  var highlightColor = '#f00';

	  function change(e)
	  {
	    if (totalCount < maxCount || e.checked == false)
	    {
	      if (e.checked == true)
	      {
	        totalCount++;
	        e.parentNode.style.backgroundColor = highlightColor;
	      } else {
	        totalCount--;
	        e.parentNode.style.backgroundColor = '';
	      }
	    } else {
	      alert('You have already selected the maximum number: ' + maxCount);
	          e.checked = false;
	    }