function showAd(pos){ 
   if (typeof(window['sAd_' + pos]) != 'undefined'){
       if (window['sAd_' + pos].toLowerCase().indexOf('<script') != -1){
           if (window['sAd_' + pos].toLowerCase().indexOf('<iframe') != -1){
               document.write(window['sAd_' + pos]);
           }
           else { document.write(window['sAd_' + pos]); }
       }
       else { document.write(window['sAd_' + pos]); }
   }
}