using System;

​

​

public class Stack {

    public void Push(object obj) {

    }

    public object Pop() {

    }

    public void Clear() {

    }

}

public class Program

{

    public static void Main()

    {

        var stack = new Stack();

        stack.Push(1);

        stack.Push(2);

        stack.Push(3);

        Console.WriteLine(stack.Pop());

        Console.WriteLine(stack.Pop());

        Console.WriteLine(stack.Pop());

    }

}