string str = "details-1-2-3-4.html";
            Match m = new Regex(@"([^-]+)(?:-([^-.]+))*").Match(str);
            StringBuilder sb = new StringBuilder();
            sb.Append(m.Groups[1].Value).Append(".aspx?id=");
            for (int i = 0; i < m.Groups[2].Captures.Count - 1; i++)
                sb.Append(m.Groups[2].Captures[i]);
            sb.Append("&p=").Append(m.Groups[2].Captures[m.Groups[2].Captures.Count - 1]);
            Console.WriteLine(sb.ToString());
            Console.ReadLine();
//details.aspx?id=123&p=4