Datetime doubt which format passed through

class Program
    {

        static void Main(string[] args)
        {
            string date = "19890428";
            DateTime dateTime;
            string[] format = { "MMddyyyy", "ddMMyyyy", "yyyyMMdd", "yyyyddMM" };
            if (DateTime.TryParseExact(date, format, CultureInfo.InvariantCulture,
                   DateTimeStyles.None, out dateTime))
            {
                Console.WriteLine( "yes" );
            }

            Console.ReadLine();

        }
    }


I get output "yes" -- by looking at the format i can know that it is yyyyMMdd so it is passed in if condition.

Is there a way to know at runtime that which format is passed.
We are consuming a webservice and the format that we are getting are not sure.It always comes as string. I don't want to do if else to check which format got passed and convert accordingly as below.  

var x = DateTime.ParseExact(cd13, "yyyyddMM", CultureInfo.InvariantCulture);

Kindly suggest.