var banner = new Array();

banner[0]='https://i.servimg.com/u/f28/14/08/99/99/banner10.png';
banner[1]='https://i.servimg.com/u/f28/14/08/99/99/banner11.png';
banner[2]='https://i.servimg.com/u/f28/14/08/99/99/banner12.png';
banner[3]='https://i.servimg.com/u/f28/14/08/99/99/banner13.png';
banner[4]='https://i.servimg.com/u/f28/14/08/99/99/banner14.png';
banner[5]='https://i.servimg.com/u/f48/14/08/99/99/banner10.png';
banner[6]='https://i.servimg.com/u/f48/14/08/99/99/banner11.png';


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