# -*- coding:utf-8 -*-
class Solution:
    def __init__(self):
        self.stack1 = []
        self.stack2 = []
    def push(self, node):
        # write code here
        self.stack1.append(node)
    def pop(self):
        # return xx
        self.stack2.append(self.stack1[0])
        self.stack1.remove(self.stack1[0])
        return self.stack2.pop()