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

namespace Gare
{
    class GenericStack<T>
    {
        protected T[] elements = new T[10];

        public GenericStack()
        {
        }

        public void push(T item)
        {
            int i = 0;
            while (elements[i] != null && i < elements.Length - 1) i++;
            elements[i] = item;
        }

        public T pop()
        {
            int i = 0;
            while (elements[i] != null && i < elements.Length - 1) i++;

            T temp = elements[i];
            T[] elementsTemp = new T[elements.Length];
            for (int k = 0;  k <  i; k++)
                elementsTemp[k] = elements[k];

            elements = elementsTemp;
            return temp;
        }

        public bool isEmpty()
        {
            return (elements[0] == null);
        }

        public bool isFull()
        {
            return (elements[elements.Length - 1] == null);
        }

        public void show()
        {
            int i = 0;
            while (elements[i] != null && i < elements.Length - 1)
                Console.Out.WriteLine(elements[i++]);
        }

        public IEnumerator<T> GetEnumerator()
        {
            int i = 0;
            while (elements[i] != null && i < elements.Length - 1)
                yield return elements[i++];
        }

        public IEnumerator<T> TopToBottom()
        {
            int i = 0;
            while (elements[i] != null && i < elements.Length - 1) i++;
            for (int j = i; j > 0; j--)
                yield return elements[j];
        }

    }
}