.net写入Cookie访问计数器

    <%    
            int last=0;
            string str = Request.Cookies["last"].Value;
            last = int.Parse(str);
            if (last != null)
            {
                Response.Write(last);
                HttpCookie acookie = new HttpCookie("last");
                acookie.Value = (last+1).ToString();
                acookie.Expires = DateTime.MaxValue;
                Response.Cookies.Add(acookie);
            }
            else
            {
                Response.Write("0");
                HttpCookie acookie = new HttpCookie("last");
                acookie.Value = "1";
                acookie.Expires = DateTime.MaxValue;
                Response.Cookies.Add(acookie);
            }
    %>