You find yourself on an island populated by three tribes: The Knights, the Knaves, and the Crazies. Each tribe dresses only in one color — a different color for each tribe. The islanders all know which tribe wears which color, but you, as an outsider, do not. When asked a yes/no question, a Knight will always answer truthfully if possible, or remain silent otherwise. (For example, if you ask him whether your next coin-flip will turn up heads, a Knight remains silent, because he can’t be sure of giving a truthful answer.) A Knave will always lie if possible, or remain silent otherwise. A Crazy will randomly tell the truth, lie, or remain silent.
And oh — one more thing. They answer in their own language, where “Cheech” means Yes and “Chong” means No — or perhaps it’s the other way around. You’ve lost your phrasebook and you can’t remember.
So you’re walking along the road, when you meet a group of three natives, one dressed in red, one dressed in blue, and one dressed in yellow. You can ask as many yes/no questions as you like, but each question must be directed to just one native.
Your goal, of course, is to figure out who belongs to which tribe.
How many questions do you need to be sure of achieving your goal?