class Message {
private:
    string text;
    static int id;
    int current_id;
public:
    Message() { current_id = ++id; }
    Message(string t){ current_id = ++id; text=t; }
    const string& get_text() {
        return text;
    }
    bool operator < (const Message& M2) {
        if(current_id < M2.current_id)
            return true;
        else
            return false;
    }
};
int Message::id = 0;
class MessageFactory {
public:
    MessageFactory() {}
    Message create_message(const string& text) {
        Message m = Message(text);
        return m;
    }
};