using System;

public class Node{

    public int Data {get;set;}

    public Node Next{get;set;}

    public int Min{get;set;}

    public Node(int val){

        Data = val;

    }

}

public class Stack{

    private Node list;

    public Stack(){

    }

    public void Push(int val){

        if(list == null){

            list = new Node(val);

            list.Min = val;

        }else{

            var newNode = new Node(val);

            newNode.Next = list;

            newNode.Min = val < list.Min ? val: list.Min;

            list = newNode;

        }

    }

    public int? Pop(){

        if(list == null)

            return null;

        int? val = list.Data;

        list = list.Next;

        return val;

    }

    public int? Min(){

        if(list == null)

            return null;

        return list.Min;

    }

}

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}