When I was a substitute teacher I would give the kids logic puzzles of varying difficulty. I would offer $100 if anyone could provide me with the answer to this one. If they looked it up on Wikipedia and could then explain it to me, I'd give them a king size candy bar.
I never had to pay out.
"The Day the Clown Cried" was released from the library of Congress last year but I haven't seen a copy so I don't know where it rates.