using System;

public class Program

{

    public static void Main()

    {

        //Console.WriteLine("0001098643426718".Substring(8,8));

        var identifier = (long)1098643426718;

        var hexId = identifier.ToString("X").PadLeft(10, '0');

        var retour = new Guid("00000000-0000-0000-0000-00" + hexId);

        Console.WriteLine(hexId);

        Console.WriteLine(retour);

    }

}