#include <iterator>
class Solution
{
public:
    void push(int node) {
        stack1.push(node);
    }

    int pop(){
        if(stack2.empty())
        
            while(!stack1.empty())
            {
                int num=stack1.top();
                stack1.pop();
                stack2.push(num);
            }
        int num=stack2.top();
        stack2.pop();
        return num;
    }

private:
    stack<int> stack1;
    stack<int> stack2;
};