// ConsoleApplication1.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
using namespace std;

struct node
{
	int data;
	node *next;
	node *prev;
};

class linked_list
{

public:

	node *head, *tail;

	linked_list()
	{
		head = NULL;
		tail = NULL;
	}

	void push(int n)
	{
		node *tmp = new node;
		(*tmp).data = n;
		tmp->next = NULL;
		tmp->prev = tail;

		if (head == NULL)
		{
			head = tmp;
			tail = tmp;
		}
		else
		{
			tail->next = tmp;
			tail = tmp;
		}
	}

	void enqueue(int n)
	{
		node *tmp = new node;
		(*tmp).data = n;
		tmp->next = head;
		tmp->prev = NULL;

		if (head == NULL)
		{
			head = tmp;
			tail = tmp;
		}
		else
		{
			head->prev = tmp;
			head = tmp;
		}
	}

	int pop()
	{
		if (tail == NULL)
		{
			return -1;
		}
		node *ptr = tail;
		int val = tail->data;
		tail = tail->prev;

		delete ptr;
		return val;
	}

	int dequeue()
	{
		if (head == NULL)
		{
			return -1;
		}
		node *ptr = head;

		int val = head->data;

		head = head->next;
		delete ptr;
		return val;
	}
};

int main()
{
	int b = 0;
	linked_list a;
	a.push(1);
	a.push(2);
	a.push(3);

	cout << a.pop();
	cout << a.dequeue();
	a.push(1);
	a.push(2);
	a.enqueue(3);
	cout << a.dequeue();
	cin >> b;
	return 0;
}