using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Queuee
{
    class Queue
    {
        Node front = null;
        Node rear = null;

        public void push(int val)
        {
            Node tmp = new Node(val);
            if (front == null && rear == null)
            {
                front = tmp;
                rear = tmp;
                return;
            }

            rear.next = tmp;
            rear = tmp;
        }

        public int top()
        {
            if (front == null)
            {
                return 0;
            }
            return front.info;
        }

        public void pop()
        {
            if (front == null)
            {
                return;
            }
            front = front.next;
        }

        public bool empty()
        {
            return (front == null);
        }

    }
}