class MyStack {
// Push element x onto stack.
Queue queue = new LinkedList<>();
public void push(int x) {
queue.add(x);
/* keep the very last element, and re-offer rest to the quue */
for(int i = 1; i < queue.size(); i++){
queue.add(queue.poll());
}
}
// Removes the element on top of the stack.
public void pop() {
queue.poll();
}
// Get the top element.
public int top() {
return queue.peek();
}
// Return whether the stack is empty.
public boolean empty() {
return queue.isEmpty();
}
}