There has been a robbery, and apparently there are two thieves working together. Enough thieves have been identified, and only two of them are guilty. Each one makes a statement, and four of the statements are true. Only two of them make false claims to cover up:
- The thief A says: C is guilty
- The thief B says: F is not guilty
- The thief C says: D is not guilty
- The thief D says: B is guilty
- The thief E says: A is not guilty
- The thief F says: E is not guilty
Who are the two guilty?
We assume that A is guilty and has made a false statement, so C is not guilty and has made a true statement. In that case D is not guilty and has made a true statement. That means that B is guilty and has made a false statement. That leads us to that E is guilty and has made a false statement.
All this gives us 4 guilty so we have to rule out that A is not guilty and tells the truth. So C is guilty and lies, that leads us to the other culprit is D.