function getCookie(c_name) {
    if (document.cookie.length > 0) {
        c_start = document.cookie.indexOf(c_name + "=");
        if (c_start != -1) {
            c_start = c_start + c_name.length + 1;
            c_end = document.cookie.indexOf(";", c_start);
            if (c_end == -1) c_end = document.cookie.length;
            return unescape(document.cookie.substring(c_start, c_end));
        }
    }
    return "";
}

function setCookie(c_name, value, expiredays) {
    var exdate = new Date();
    exdate.setDate(exdate.getDate() + expiredays);
    document.cookie = c_name + "=" + escape(value) + ((expiredays == null) ? "" : ";expires=" + exdate.toUTCString());
}
var speed = 300;
var num = ((getCookie("backgroundpos") != "") ? (parseInt(getCookie("backgroundpos"))) : 800);
var bgOb = eval('document.body');
function scrollBG() {
    num--;
    if (num <= 0)
        num = 800;
    setCookie("backgroundpos", num, 1);
    bgOb.style.backgroundPosition = "0" + num + "px";
}
setInterval('scrollBG()', speed);