var how_many_ads = 23 
var now = new Date() 
var sec = now.getSeconds() 
var ad = sec % how_many_ads; 
ad +=1; 

if (ad==1){ 
banner="/image/topbg/01.jpg"; 
 
} 

if (ad==2) {   
banner="/image/topbg/02.jpg"; 
} 
  
if (ad==3) { 
banner="/image/topbg/03.jpg"; 
}

if (ad==4) { 
banner="/image/topbg/04.jpg"; 
}  

if (ad==5) { 
banner="/image/topbg/05.jpg"; 
}  
  
if (ad==6) { 
banner="/image/topbg/06.jpg"; 
}  
if (ad==7) { 
banner="/image/topbg/07.jpg";  
}  
if (ad==8) { 
banner="/image/topbg/08.jpg"; 
}  
if (ad==9) { 
banner="/image/topbg/09.jpg";  
}  
if (ad==10) { 
banner="/image/topbg/10.jpg";  
}  
if (ad==11) { 
banner="/image/topbg/11.jpg";   
}  
if (ad==12) { 
banner="/image/topbg/12.jpg"; 
}  
if (ad==13) { 
banner="/image/topbg/13.jpg"; 
}  
if (ad==14) { 
banner="/image/topbg/14.jpg";  
}  
if (ad==15) { 
banner="/image/topbg/15.jpg";  
}  
if (ad==16) { 
banner="/image/topbg/16.jpg"; 
}  
if (ad==17) { 
banner="/image/topbg/17.jpg";  
}  
if (ad==18) { 
banner="/image/topbg/18.jpg";  
}  
if (ad==19) { 
banner="/image/topbg/19.jpg";   
}  
if (ad==5) { 
banner="/image/topbg/05.jpg";   
}  
if (ad==20) { 
banner="/image/topbg/20.jpg";   
}  
if (ad==5) { 
banner="/image/topbg/05.jpg"; 
}  
if (ad==21) { 
banner="/image/topbg/21.jpg";   
}  
if (ad==22) { 
banner="/image/topbg/22.jpg"; 
}  
if (ad==23) { 
banner="/image/topbg/23.jpg"; 
} 
document.write('<img src=\"' + banner + '\" width=336 height=126 border=0>');