using System;

public class Program

{

    public static void Main()

    {Stack mystack=new Stack();

        mystack.push(10);

        mystack.push(20);

        mystack.push(50);

        Console.WriteLine(mystack.count);

        Console.WriteLine(mystack.Peek());

        Console.WriteLine(mystack.Peek());

        Console.WriteLine(mystack.count);

        mystack.clear();

        Console.WriteLine(mystack.count);

     ///push     pop     count  peek  

    }

}