var width   = "737";        // Width of Advertisements
var height  = "150";        // Height of Advertisements 
var target  = "_blank";     // Target window to open the ads

var ad=new Array()
// Write down the source urls of ad images
ad[0]='1.jpg';
ad[1]='2.jpg';
ad[2]='3.jpg';
ad[3]='4.jpg';
ad[4]='5.jpg';

var links=new Array()

links[0]='link0';
links[1]='link1';
links[2]='link2';
links[3]='link3';
links[4]='link4';

var s = Math.floor(Math.random()*ad.length);
document.write('<a href="'+links[s]+'" target="'+target+'"><img src="'+ad[s]+'" width="'+width+'" height="'+height+'" border="0" alt="'+links[s]+'"></a>');