var imagenumber=12;
var randomnumber=Math.random();
var banner1=Math.round((imagenumber-1)*randomnumber)+1;

images=new Array
images[1]="../images/ads/ad_zgcb_ari.jpg"
images[2]="../images/ads/ad_zgcb_tau.jpg"
images[3]="../images/ads/ad_zgcb_can.jpg"
images[4]="../images/ads/ad_zgcb_gem.jpg"
images[5]="../images/ads/ad_zgcb_leo.jpg"
images[6]="../images/ads/ad_zgcb_vir.jpg"
images[7]="../images/ads/ad_zgcb_lib.jpg"
images[8]="../images/ads/ad_zgcb_sco.jpg"
images[9]="../images/ads/ad_zgcb_sag.jpg"
images[10]="../images/ads/ad_zgcb_aqu.jpg"
images[11]="../images/ads/ad_zgcb_cap.jpg"
images[12]="../images/ads/ad_zgcb_pis.jpg"

var image=images[banner1]