using System;

    using System.Collections.Generic;

​

    public interface Iterator

    {

        string Current();

        bool HasNext();

        void Next();

    }

​

    public class BrowserHistory 

    {

        private string[] urls = new string[10];

        private int count = 0;

        public void Push(string url)

        {

            urls[count] = url;

            count++;

        }

        public string Pop()

        {

            count--;

            return urls[count];

        }

        public Iterator CreateIterator() {

            return new ArrayIterator(this);

        }

        public class ArrayIterator: Iterator

        {

            private BrowserHistory history;

            private int index = 0;

            public ArrayIterator(BrowserHistory history)

            {

                this.history = history;

            }

            public string Current()

            {

                return history.urls[index];

            }

            public bool HasNext() 

            {

                return index < history.count;

            }

            public void Next()

            {

                index++;

            }

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            var history = new BrowserHistory();

            history.Push("website1");

            history.Push("website2");

            history.Push("website3");

            var iterator = history.CreateIterator();

            while(iterator.HasNext()) 

            {

                Console.WriteLine(iterator.Current());

                iterator.Next();

            }

        }

    }