using System;

using System.Collections;

​

public class Program

{

    Stack stc1 = new Stack();

    Stack stc2 = new Stack();

    public class Queue

    {

        public int rear;

        public int[] el;

        public int front;

        public int max;

        public Queue(int size)

        {

            el = new int[size];

            rear = -1;

            front = 0;

            max = size;

        }

​

        public void Enqueue(int item)

        {

            if (rear == max - 1)

            {

                Console.WriteLine("Overflowed");

                return;

            }

            else

            {

                el[++rear] = item;

            }

        }

​

        public int dequeue()

        {

            if (front == rear + 1)

            {

                Console.WriteLine(-1);

                return -1;

            }

            else

            {

                Console.WriteLine(el[front]);

                int p = el[front++];

                Console.WriteLine();

                return p;

            }

        }

    }

​

    public static void Main()

    {

        int[] arr = new int[]{1, 2, 1, 3, 2, 1, 4, 2};

        Queue obj = new Queue(arr.Length);

        for (int i = 0; i < arr.Length; i++)

        {

            if (arr[i] == 1 && i != arr.Length - 1)

            {

                obj.Enqueue(arr[i + 1]);

                i = i + 1;

            }

            else

            {

                if (arr[i] != 1)

                {

                    obj.dequeue();

                }

            }

        }

    }

}