static void Main(string[] args)
        {
            LinkedList <int> list = new LinkedList <int>();

            Console.WriteLine($"Hello World! {list.GetSize()}");
            list.Add(1, 2, 3, 4, 5, 6, 7, 8, 9);
            Console.WriteLine($"Linked list now has {list.GetSize()} elements.\n{list.ToString()}");
        }