In a strange village there are three kinds of persons: knights (always telling the truth), knaves (always lying) and jokers (who may either tell the truth or lie).
A, B, C and D live in this village, and, among them, we know that there is a knight, a knave and a joker, plus a fourth person whose kind we don't know.
Also, among B and D there is one knight and one knave.
Each of them says something.
- A: "The person whose kind you don't know is a knave"
- B: "A and D are a joker and a knave (not necessarily in this order)"
- C: "D is not telling the truth"
- D: "At least one among A and C tells the truth"
Determine the kind of A, B, C, and D.