# -*- coding:utf-8 -*-

class Solution:

    def __init__(self):

        self.stack = []

        self.min_stack = []

    def push(self, node):

        # write code here

        self.stack.append(node)

        if not self.min_stack or node <= self.min_stack[-1]:

            self.min_stack.append(node)

        else:

            self.min_stack.append(self.min_stack[-1])

    def pop(self):

        # write code here

        #if not self.stack:

        self.stack.pop()

        self.min_stack.pop()

    def top(self):

        # write code here

        return self.stack[-1]

    def min(self):

        # write code here

        return self.min_stack[-1]