You arrive in a country whose populations are humans and zombies. Humans always tell the truth, while zombies always lie. However, both humans and zombies can be stable or crazy. If an inhabitant is crazy, she will believe that a truth statement is false, and a false statement is true. Stable inhabitants believe that truth statements are true and false statements are false. Thus stable humans and crazy zombies make only true statements, while crazy humans and stable zombies make only false statements. You meet two people, X and Y. You know that one of them is a human, and the other is a zombie. X tells you: "we are both crazy", while Y tells you that "at least one of us is stable". From this, can you find which one is the zombie?