using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace D04._1
{
    class Program
    {
        static byte[] ToB(string str) => Encoding.ASCII.GetBytes(str);
        static string ToS(byte[] b) => BitConverter.ToString(b).Replace("-", "");

        static void Main(string[] args)
        {
            if (args.Length < 1) throw new ArgumentException();

            string hash = args[0];

            int nbr = 0;
            using (var md5 = MD5.Create())
            {
                do
                {
                    var h = md5.ComputeHash(ToB($"{hash}{nbr}"));
                    if (ToS(h).StartsWith("00000")) break;

                    nbr++;
                } while (true);
            }

            Console.WriteLine($"Answer is : {nbr}");
        }
    }
}