How to redirect to the last message created???

[grafic.web]

Hi there, this is the code of my contactcontroller.cs :

using ContactMvc.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;



    namespace ContactMvc.Controllers
    {
        public class ContactController : Controller
        {
            //
            // GET: /Contact/

            [HttpGet]
            public ActionResult Index()
            {
                return View(new ContactMessage());
            }

            [HttpPost]
            [ValidateAntiForgeryToken]
            public ActionResult Index(ContactMessage post)
            {
                if (ModelState.IsValid)
                {
                    using (var db = new ContactDatabase())
                    {
                        post.DateSent = DateTime.Now;

                        db.ContactMessages.Add(post);

                        db.SaveChanges();
                    }

                    TempData["ContactMessage"] = post;
                    return RedirectToAction("SuccessfulMessage");
                }

                return View(post);
            }

            public ActionResult SuccessfulMessage()
            {
                var message = (ContactMessage)TempData["ContactMessage"];

                return View(message);                                  
            }

            [NonAction]
            public ActionResult LogList()
            {
                var messages = new List<ContactMessage>();

                using (var db = new ContactDatabase())
                {
                    messages.AddRange(db.ContactMessages.ToArray());
                }

                return View(messages);
            }


            public ActionResult Log(int? id = null)
            {
                if (!id.HasValue)
                {
                    return LogList();
                }

                using (var db = new ContactDatabase())
                {
                    var message = db.ContactMessages.SingleOrDefault(m => m.ID == id);

                    if (message != null)
                    {
                        return View("LogSingle", message);
                    }
                }

                return new HttpNotFoundResult();
            }

        }
    }

How can i go straight away to the page where i i can show my message created (get the id of the last message and show it)???

Thanks