public static boolean P(Deque from, Deque to, Stack s) {
        if (from.size() != 0) {
            s.push(from.getFirst());
            from.removeFirst();
            return true;
        } else
            return false;
    }

    public static boolean V(Deque from, Deque to, Stack s) {
        if (s.size() != 0) {
            to.addFirst(s.pop());
            return true;
        } else
            return false;
    }

    //请实现go函数
    public static void go(Deque from, Deque to, Stack s) {

        if(to.size()==9)
            answers++;

        Deque f = from.clone();
        Deque t = to.clone();
        Stack stack = s.clone();

        //if(stack.size()<4) {
            if (P(from, to, s))// P V选择错误 则不继续迭代
                go(from, to, s);
        //}

        if (V(f, t, stack))
            go(f, t, stack);

    }