var max = 10;
var nrImages = 4;
function makeImages() {
this[0] = "http://www.apriori.com.br/cgi/for/images/apriori_sursis.jpg";
this[1] = "http://www.these.com.br/images/these_sursis.jpg";
this[2] = "http://www.iuris.com.br/images/iuris_sursis.jpg";
this[3] = "http://www.sursis.com.br/images/sursis.jpg";
this.length = nrImages;
}
function makeLinks() {
this[0] = "http://www.apriori.com.br";
this[1] = "http://www.these.com.br";
this[2] = "http://www.iuris.com.br";
this[3] = "http://www.sursis.com.br";
this.length = nrImages;

}
var vetImages = new makeImages();
var vetLinks = new makeLinks();
var x = Math.round(Math.random()*max);
var y = max / nrImages;
for(var cont = 1;cont*y<= max;cont++) {
if (x <= (cont*y)) {
document.write("<a href="+vetLinks[cont-1]+" target=_blank><img src="+vetImages[cont-1]+" border=0></a>");
break;
}
}