using System;
using System.Collections.Generic;
using System.Text;
 
namespace EnumTest
{
	class Program
	{
		static void Main(string[] args)
		{
		Stack<int> s = new Stack<int>();
		}
	}
	public class Stack<T> : IEnumerable<T>
	{
		T[] items = new T[100];
		int count;
 
		public void Push(T data) { ... }
 
		public T Pop() { ... }
 
		public IEnumerator<T> GetEnumerator()
		{
			for(int i = count - 1; i >= 0; --i)
			{
				yield return items;
			}
		}
	}
}