Abe, Ben and Cal live on a remote island inhabited by three groups: the Knights, the Liars and the Knaves. Precisely one of them is a Knight, who always tells the truth, another is a Liar, who always lies, and the remaining one is a Knave, who alternately tells the truth and a lie.

One of the three men is the President of the island.

Abe says:
(1) “The President belongs to a different group from each of the other two of us".
(2) “Ben is not the President".

Ben says:
(1) "The President is a Liar".
(2) "Abe is not the President”.

Cal says:
(1) "Exactly two of us belong to the same group".
(2) "I am not the President".

Who is the President?