var mess = new Array('<img alt="" src="images/index_image.jpg" width="852" height="350" />','<img alt="" src="images/index_image2.jpg" width="852" height="350" />','<img alt="" src="images/index_image3b.jpg" width="852" height="350" />','<img alt="" src="images/index_image4.jpg" width="852" height="350" />');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);