using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
Stack<int> a = new Stack<int>();
a.Push(4);
a.Push(7);
a.Push(1);
foreach(var x in a)
Console.WriteLine(x);
}
Console.WriteLine("peek is ...." + a.Peek());
Console.WriteLine("pop is ...." + a.Pop());