var banner = new Array();

banner[0]='https://i.servimg.com/u/f88/14/48/37/50/shot0210.jpg';
banner[1]='https://i.servimg.com/u/f88/14/48/37/50/shot0211.jpg';
banner[2]='https://i.servimg.com/u/f88/14/48/37/50/shot0213.jpg';

document.getElementById('logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];

setInterval("document.getElementById('logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];",5000);