Implement the following operations of a stack using queues.

• push(x) -- Push element x onto stack.
• pop() -- Removes the element on top of the stack.
• top() -- Get the top element.
• empty() -- Return whether the stack is empty.

class MyStack {

    private Queue<Integer> q1;
    private Queue<Integer> q2;

    /** Initialize your data structure here. */
    public MyStack() {
        q1 = new LinkedList<>();
        q2 = new LinkedList<>();
    }

    /** Push element x onto stack. */
    public void push(int x) {
        q1.offer(x);
    }

    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        while(q1.size() > 1) {
            q2.offer(q1.poll());
        }

        int res = q1.poll();
        while(q2.size() > 0) {
            q1.offer(q2.poll());
        }

        return res;
    }

    /** Get the top element. */
    public int top() {
        while(q1.size() > 1) {
            q2.offer(q1.poll());
        }

        int res = q1.poll();
        q2.offer(res);
        while(q2.size() > 0) {
            q1.offer(q2.poll());
        }

        return res;
    }

    /** Returns whether the stack is empty. */
    public boolean empty() {
        return q1.isEmpty();
    }
}

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack obj = new MyStack();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.top();
 * boolean param_4 = obj.empty();
 */