class FoodOrdersApp:
    def __init__(self):
        self.menu = []
        self.clients_list = []

    def register_client(self, client_phone_number: str):
        for client in self.clients_list:
            if client.phone_number == client_phone_number:
                raise Exception("The client has already been registered!")
        new_client = Client(client_phone_number)
        self.clients_list.append(new_client)
        return f"Client {client_phone_number} registered successfully."

    def add_meals_to_menu(self, *meals: Meal):
        self.menu = [meal for meal in meals if meal.__class__.__name__ in ["Starter", "MainDish", "Dessert"]]

    def show_menu(self):
        if len(self.menu) < 5:
            raise Exception("The menu is not ready!")
        result = ""
        for meal in self.menu:
            result += meal.details() + "\n"
        return result