using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var t1 = new List<string> { "123", "Jack", "Jill", "777" };

        var t2 = new List<string> { "123", "Jack", "Noll", "777" };

        var t3 = new List<string> { "123", "Nock", "Noll", "777" };

        var t4 = new List<string>();

        var tests =  new List<List<string>> {t1, t2, t3, t4 };

        foreach (var test in tests)

        {

            var names = new LinkedList<string>(test);

            string result = names.Count > 0 ? null : "Herbert";

            while (names.Count > 0) {

                var name_ = names.Last.Value;

                if (name_ == "Jack" || name_ == "Jill") {

                    result = name_;

                    break;

                }

                result = name_;

                names.RemoveLast();

            }

            Console.WriteLine("Hello, " + result);

        }

    }

}