using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(CreatePlayFabTitleId(0x3B3F3A1A));

        //Console.WriteLine(CreatePlayFabTitleIdString(new Guid("d0d24afc-5526-4340-9c0f-12c791b5ada0")));

    }

    private static readonly byte[] PlayFabTitleIdPrefix = BitConverter.GetBytes(0xFFFFFFFFFFFFFFFF);

    public static string CreatePlayFabTitleIdString(Guid guidTitleId)

    {

        byte[] guidBytes = guidTitleId.ToByteArray();

        return BitConverter.ToUInt64(guidBytes, PlayFabTitleIdPrefix.Length).ToString("X");

    }

    public static Guid CreatePlayFabTitleId(ulong longTitleId)

    {

        return new Guid(PlayFabTitleIdPrefix.Concat(BitConverter.GetBytes(longTitleId)).ToArray());

    }

}