public ActionResult Login(User u)
 {
     if (ModelState.IsValid)
     {
         DataAbstractionLayer dal = new DataAbstractionLayer();
         int authenticatedUserId  = dal.Authenticate(u);
         if (authenticatedUserId != -1)
         {
             Session["LoggedUserID"] = authenticatedUserId;
             return(RedirectToAction("Index", "Main"));
         }
     }
     return(View("LoginFailedView"));
 }