function changeImage(image_id){

    cur_image++;
    if (cur_image > images_number){
        cur_image = 1;
    }

    var my_img = document.getElementById(image_id);

    my_img.src = eval('img_' + cur_image  + '.src');

    timeout = setTimeout(function (){ changeImage(image_id) },5000);

}

function showImage(image_id, img_num){

    cur_image = img_num - 1;
    clearTimeout(timeout);
    changeImage(image_id);

}