public HttpResponse Create(CreateInputModel model)
        {
            var  name           = model.Name.ToLower();
            var  points         = model.Points;
            bool isProblemExist = problemService.IsProblemExist(name);

            if (!IsUserSignIn())
            {
                return(Redirect("/Users/Login"));
            }

            if (string.IsNullOrWhiteSpace(name) || 5 > name.Length || name.Length > 20 || isProblemExist)
            {
                return(Error("The name should be between 5 and 20 charachters long."));
            }

            if (50 > points || points > 300)
            {
                return(Error("The points should be a number between 50 and 300 ."));
            }

            problemService.AddProblem(name, points);

            return(Redirect("/"));
        }