(function(){
  var user_id=parent.bt_user_id;
  var site_id=parent.bt_site_id;
  var size=parent.bt_size;
  if (!size || !site_id || !user_id){
    user_id=bt_user_id;
    site_id=bt_site_id;
    size=bt_size;
  }

  var rand = Math.floor(Math.random()*100000000);
  var d1 = new Date().getTime();
  var d2 = new Date().getTime();
  while(!size || !site_id || !user_id){
    user_id=parent.bt_user_id;
    site_id=parent.bt_site_id;
    size=parent.bt_size;

    if(d2 < d1 + 3000){
      user_id=0;
      site_id=0;
      size=0;
      break;
    }
  }

  if(size && site_id && user_id){
    var bimg = 'http://b2.banner-trade.net/ads/'+user_id+'/'+site_id+'/'+size+'/'+rand+'/';
    var blink = 'http://b2.banner-trade.net/adslink/'+user_id+'/'+site_id+'/'+size+'/'+rand+'/';
    document.write('<a href="'+blink+'"><img src="'+bimg+'" style=""></a>');
  }

})()