import java.io.*;
class LinkedList {
	Node head;

	class Node {
		int data;
		Node next;
		Node(int d)
		{
			data = d;
			next = null;
		}
	}

	void printMiddle()
	{
		Node slow_ptr = head;
		Node fast_ptr = head;

		while (fast_ptr != null && fast_ptr.next != null) {
			fast_ptr = fast_ptr.next.next;
			slow_ptr = slow_ptr.next;
		}
		System.out.println("The middle element is ["
						+ slow_ptr.data + "] \n");
	}

	public void push(int new_data)
	{
		Node new_node = new Node(new_data);

		new_node.next = head;

		head = new_node;
	}
	public void printList()
	{
		Node tnode = head;
		while (tnode != null) {
			System.out.print(tnode.data + "->");
			tnode = tnode.next;
		}
		System.out.println("NULL");
	}

	public static void main(String[] args)
	{
		LinkedList llist = new LinkedList();
		for (int i = 5; i > 0; --i) {
			llist.push(i);
			llist.printList();
			llist.printMiddle();
		}
	}
}