$PI When we were kids, we learned a fable called "The Boy Who Cried Wolf." When the shepherd boy shouted "Wolf is coming! Wolf is coming!", the adults believed him and went out to hunt the wolf, but there was no wolf. Later, the shepherd boy cried wolf again, and the adults chose to believe him again and went to look for the wolf, but the wolf still didn't come. Therefore, the adults got angry and stopped believing the shepherd boy. The third time, the wolf really came, and the shepherd boy shouted "Wolf is coming! Wolf is coming!", but this time the adults no longer believed the shepherd bo