class QueueFullException extends RuntimeException {}
class QueueEmptyException extends RuntimeException {}

class ThreadSafeQueue<T> {
    private final Object lock = new Object();
    private final T[] queue;
    private int size = 0;
    private int front = 0;
    private int rear = 0;

    @SuppressWarnings("unchecked")
    public ThreadSafeQueue() {
        queue = (T[]) new Object[10];
    }

    public void enqueue(T item) {
        synchronized (lock) {
            if (size >= 10) throw new QueueFullException();
            queue[rear] = item;
            rear = (rear + 1) % queue.length;
            size++;
        }
    }

    public T dequeue() {
        synchronized (lock) {
            if (size == 0) throw new QueueEmptyException();
            T item = queue[front];
            front = (front + 1) % queue.length;
            size--;
            return item;
        }
    }
}