//
//	P.130
//

import java.util.*;
class IntegerLinkedListDemo
{
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		boolean go = true;
		String answer;
		int temp;

		LinkedList<Integer> list = new LinkedList<Integer>();

		while(go)
		{
			menu();
			answer = input.next();
			if(answer.equalsIgnoreCase("P"))
			{
				System.out.println("\nPush an integer on top: ");
				temp = input.nextInt();
				list.push(temp);
			}
			else if(answer.equalsIgnoreCase("O"))
			{
				System.out.println("\nPop the top integer: ");
				list.pop();
			}
			else if(answer.equalsIgnoreCase("S"))
			{	// p.131
				System.out.println("\nThe list is: " + list);
				System.out.println();
			}
			else if(answer.equalsIgnoreCase("Q"))
				go = false;
		}
		System.out.println("\n\nDone.\n\n");
	}

	public static void menu()
	{
		System.out.println("\n\n---------------------");
		System.out.println("P	Push an item");
		System.out.println("S	Show the list");
		System.out.println("O	Pop an item");
		System.out.println("Q	Quit");
	}
}