Ha, the first one is cute. It's stolen almost directly from some CS competition training problems I did back in high school. I saw it and _knew_ I'd seen it be

Ha, the first one is cute. It's stolen almost directly from some CS competition training problems I did back in high school. I saw it and _knew_ I'd seen it before. ;) (edited to remove the name of the competition, since it turns out some answers are Googleable :-\)