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; };