using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var calc =new AverageCalculator();

        Console.WriteLine(calc.GetAvg(1));

        Console.WriteLine(calc.GetAvg(1));

        Console.WriteLine(calc.GetAvg(1));

        Console.WriteLine(calc.GetAvg(2));

        Console.WriteLine(calc.GetAvg(3));

    }

    public class AverageCalculator 

    {

        private Queue<decimal>_queue = new Queue<decimal>();

        private decimal _sum = 0;

        private int _maxQueueSize;

​

        public AverageCalculator()

        {

            _maxQueueSize = 3;

        }

        public decimal GetAvg(decimal newItem)

        {

            _queue.Enqueue(newItem);

            if(_queue.Count > _maxQueueSize)

            {

                var head = _queue.Dequeue();

                _sum-=head;

            }

            _sum+=newItem;

            return _sum/_queue.Count;

        }

    }

}