function IsCookie (name) { 
    var arg = name + "="; 
    var alen = arg.length; 
    var clen = document.cookie.length; 
    var i = 0; 
    while (i < clen) { 
      var j = i + alen; 
      if (document.cookie.substring(i, j) == arg) 
        return true; 
      i = document.cookie.indexOf(" ", i) + 1; 
      if (i == 0) break; 
    } 
    return null;
  }
  var ad_entry = 0;
  if (navigator.cookieEnabled && !IsCookie("ad_entry")) 
  {
    document.cookie = "ad_entry=1";
    ad_entry = 1;
  }