function randomAd() {
    var tmp = Math.round(Math.random());
    if (tmp == 0) {
        document.write("<img class=\"ad\" width=\"186\" height=\"120\" border=\"0\" alt=\"Call 13 14 69\" src=\"./images/ad_1.jpg\"/>")
    } else {
        document.write("<img class=\"ad\" width=\"186\" height=\"120\" border=\"0\" alt=\"Call 13 14 69\" src=\"./images/ad_1.jpg\"/>")
    }
}