#include <iostream>
#include <cstdlib>

struct Node {
	Node *ptr;
	int data;
};

class custom_queue {
public:
	custom_queue() {
		head = NULL;
		tail = NULL;
	};
	~custom_queue() {
		while (head != NULL)
			dequeue();
	};
	void enqueue(int a) {
		Node *temp = tail;
		Node *insert = new Node();
		insert->ptr = NULL;
		insert->data = a;
		if (tail != NULL)
			temp->ptr = insert;
		else
			head = insert;
		tail = insert;
	}
	void dequeue() {
		if (head != NULL) {
			Node *old = head;
			head = old->ptr;
			if (head == NULL)
				tail = NULL;
			delete old;
		}
	}
	void print() {
		Node *temp = head;
		while (temp != NULL) {
			std::cout << temp->data << " ";
			temp = temp->ptr;
		}
		std::cout << std::endl;
	}
private:
	Node *head;
	Node *tail;
};

void main() {
	custom_queue *q = new custom_queue;
	q->enqueue(0);
	q->enqueue(1);
	q->enqueue(2);
	q->enqueue(3);
	q->enqueue(4);
	q->dequeue();
	q->print();
	delete q;
}