using System;

public class Program

{

    enum TTT {

       A = 1,

       B = 2

    }

    const int NumDigits = 6;

    public static void Main()

    {

        Guid serviceId = Guid.NewGuid();

        int prefix = Math.Abs(serviceId.GetHashCode() % (int)Math.Pow(10, NumDigits)) * 1000;

        Console.WriteLine(prefix + TTT.B);

    }

}

​