var banner = new Array();

banner[0]='https://i.servimg.com/u/f27/15/67/86/84/110.jpg';
banner[1]='https://i.servimg.com/u/f27/15/67/86/84/210.jpg';
banner[2]='https://i.servimg.com/u/f27/15/67/86/84/310.jpg';
banner[3]='https://i.servimg.com/u/f27/15/67/86/84/410.jpg';

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