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

namespace Kolos_Algorytmy_v2
{
    class Queue
    {
        int?[] array;
        int head = 0, tail = 0, size = 0;
        public Queue(int size)
        {
            array = new int?[size];
        }

        public void Enque(int number)
        {
            if (size != array.Length)
            {
                size++;
                array[tail++] = number;
                tail = tail % array.Length;
            }
        }

        public int? Deque()
        {
            int? back= null;
            if (size != 0)
            {
                back = array[head];
                array[head] = null;
                size--;
                head = (head + 1) % array.Length;

            }
            return back;
        }
    }
}