jumpURL = new Array();
imgURL  = new Array();
jumpURL[0] = "http://enseki.com/";
jumpURL[1] = "http://enseki.com/";
jumpURL[2] = "http://enseki.com/";
jumpURL[3] = "http://enseki.com/";
imgURL[0]  = "/user_data/packages/default/img/top/img_main.jpg";
imgURL[1]  = "/user_data/packages/default/img/top/img_main2.jpg";
imgURL[2]  = "/user_data/packages/default/img/top/img_main3.jpg";
imgURL[3]  = "/user_data/packages/default/img/top/img_main4.jpg";

n = Math.floor(Math.random()*jumpURL.length);
document.write("<img src='"+imgURL[n]+"' border='0'>");