That's exactly the puzzle! If you'd like a hint, imagine that there are only two villagers - you're one of them, and the other one has a blue dot. A visitor te

That's exactly the puzzle! If you'd like a hint, imagine that there are only two villagers - you're one of them, and the other one has a blue dot. A visitor tells you both "there is at least one blue". You already knew that, but did he? And what happens the following day, when you see him still alive (or don't)?