class Solution
{
public:
    void push(int node) 
    {
        stack1.push(node);
    }

    int pop() 
    {
        while(stack1.empty()!=1)
        {
            int x=stack1.top();
            stack2.push(x);
            stack1.pop();
        }
        int y=stack2.top();
        stack2.pop();
        while(stack2.empty()!=1)
        {
            int x=stack2.top();
            stack1.push(x);
            stack2.pop();
        }
        return y;
    }

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