using System;

​

public class Program

{

    public static void Main()

    {

        LinkedList myList1 = new LinkedList();

        for (var i = 51; i > 0; i--)

        {

            myList1.AddFirst("Hello node : " + i);

        }

        myList1.printItemInTheMiddle();

    }

    public class Node

    {

        public Node next;

        public Object data;

    }

    public class LinkedList

    {

        private Node head;

        public void printItemInTheMiddle()

        {

            Node slow_ptr = head;

            Node fast_ptr = head;

​

            if (head != null)

            {

                while (fast_ptr != null &&

                       fast_ptr.next != null)

                {

                    fast_ptr = fast_ptr.next.next;

                    slow_ptr = slow_ptr.next;

                }

                Console.WriteLine("The middle element is [" + slow_ptr.data + "] \n");

            }

        }

        public void AddFirst(Object data)

        {

            Node toAdd = new Node();

​

            toAdd.data = data;

            toAdd.next = head;

​

            head = toAdd;

        }

        public void AddLast(Object data)

        {

            if (head == null)

            {

                head = new Node();

​

                head.data = data;

                head.next = null;

            }

            else

            {

                Node toAdd = new Node();

                toAdd.data = data;

​

                Node current = head;

                while (current.next != null)

                {

                    current = current.next;

                }

                current.next = toAdd;

            }

        }

    }

}