#include <iostream>

#define MAX_SIZE 10

class CircularQueue {
private:
    int front, rear;
    int queue[MAX_SIZE];

public:
    CircularQueue() {
        front = -1;
        rear = -1;
    }

    bool isEmpty() {
        return front == -1 && rear == -1;
    }

    bool isFull() {
        return (rear + 1) % MAX_SIZE == front;
    }

    void enqueue(int value) {
        if (isFull()) {
            std::cout << "Queue is full. Cannot enqueue.\n";
            return;
        }

        if (isEmpty()) {
            front = 0;
            rear = 0;
        } else {
            rear = (rear + 1) % MAX_SIZE;
        }

        queue[rear] = value;
        std::cout << value << " enqueued to the queue.\n";
    }

    void dequeue() {
        if (isEmpty()) {
            std::cout << "Queue is empty. Cannot dequeue.\n";
            return;
        }

        std::cout << queue[front] << " dequeued from the queue.\n";

        if (front == rear) {
            front = -1;
            rear = -1;
        } else {
            front = (front + 1) % MAX_SIZE;
        }
    }

    void display() {
        if (isEmpty()) {
            std::cout << "Queue is empty.\n";
            return;
        }

        int i = front;
        while (i != rear) {
            std::cout << queue[i] << " ";
            i = (i + 1) % MAX_SIZE;
        }
        std::cout << queue[rear] << "\n";
    }
};

int main() {
    CircularQueue q;

    q.enqueue(10);
    q.enqueue(20);
    q.enqueue(30);
    q.display();

    q.dequeue();
    q.display();

    q.enqueue(40);
    q.display();

    return 0;
}