var bgc = new Array();
bgc[0] = "url(top_20100721/top_100721_1.jpg)";
bgc[1] = "url(top_20100721/top_100721_2.jpg)";
bgc[2] = "url(top_20100818/top_100818_1.jpg)";
bgc[3] = "url(top_20100818/top_100818_3.jpg)";
bgc[4] = "url(top_20100818/top_100818_4.jpg)";
bgc[5] = "url(top_20100818/top_100818_6.jpg)";
bgc[6] = "url(top_20100818/top_100818_7.jpg)";
bgc[7] = "url(top_20100818/top_100818_8.jpg)";
bgc[8] = "url(top_20100818/top_100818_9.jpg)";
bgc[9] = "url(top_20100818/top_100818_10.jpg)";
n = Math.floor(Math.random()*bgc.length);
document.body.style.backgroundImage = bgc[n]