import java.util.List;

// La superclase frágil: la subclase se rompe por un detalle interno de HashSet.
public class FragileDemo {
    public static void main(String[] args) {
        CountingSet inherited = new CountingSet();
        inherited.addAll(List.of("arroz", "azúcar", "aceite"));
        IO.println("herencia:    added() = " + inherited.added());

        DelegatingCountingSet composed = new DelegatingCountingSet();
        composed.addAll(List.of("arroz", "azúcar", "aceite"));
        IO.println("composición: added() = " + composed.added());
    }
}