class MyQueue {
    Stack<Integer> inStack;
    Stack<Integer> outStack;

    public MyQueue() {
        this.inStack = new Stack<>();
        this.outStack = new Stack<>();
    }
    
    public void push(int x) {
        while(!outStack.isEmpty()){
            inStack.push(outStack.pop());
        }
        inStack.push(x);
        while(!inStack.isEmpty()){
            outStack.push(inStack.pop());
        }
    }
    
    public int pop() {
        if(outStack.isEmpty()){
            return -1;
        }
        return outStack.pop();
    }
    
    public int peek() {
        if(outStack.isEmpty()){
            return -1;
        }
        return outStack.peek();
    }
    
    public boolean empty() {
        return outStack.isEmpty();
    }
}

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

class MyStack {

    Deque<Integer> que1;

    public MyStack() {
        que1 = new ArrayDeque<>();
    }
    
    public void push(int x) {
        que1.addLast(x);
    }
    
    public int pop() {
        int size = que1.size();
        size--;
        while (size-- > 0){
            que1.addLast(que1.peekFirst());
            que1.pollFirst();
        }
        int res = que1.pollFirst();
        return res;
    }
    
    public int top() {
        return que1.peekLast();
    }
    
    public boolean empty() {
        return que1.isEmpty();
    }
}