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);
}