public static string AcquireTokenSilent(Dictionary <string, string> input)
        {
            AuthenticationContext ctx = new AuthenticationContext("");
            string output             = string.Empty;

            try
            {
                AuthenticationResult result = ctx.AcquireTokenSilentAsync("", "").Result;
                output = result.ToJson();
            }
            catch (Exception exc)
            {
                output = exc.InnerException.Message;
            }

            return(output);
        }