var how_many_ads = 6;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;
if (ad==1) { url='<a target="_blank" href="http://www.n6n.com/" title="العاب فلاش"><img src="http://www.66z.com/advertise/2.gif" alt="" /></a>'; }
if (ad==2) { url='<a target="_blank" href="http://dora.66z.com/" title="العاب دورا"><img src="http://www.66z.com/advertise/4.gif" alt="" /></a>'; }
if (ad==3) { url='<a target="_blank" href="http://nickelodeon.66z.com" title="العاب نكلودين"><img src="http://www.66z.com/advertise/5.gif" alt="" /></a>'; }
if (ad==4) { url='<a target="_blank" href="http://sonic.66z.com/" title="العاب سونيك"><img src="http://www.66z.com/advertise/6.gif" alt="" /></a>'; }
if (ad==5) { url='<a target="_blank" href="http://sponge-bob.66z.com/" title="العاب سبونج بوب"><img src="http://www.66z.com/advertise/7.gif" alt="" /></a>'; }

document.write(url);