Alan, Ben, Chris, Dave and Emma are eating a big cake. After eating, there was one slice left, and they decided to leave it for Frank but someone ate it! Frank knows that each of these 5 people are each telling one truth and one lie:
Alan said:
It was Emma,
It wasn't Ben.
Ben said:
It wasn't Chris,
It was Alan.
Chris said:
It was Ben,
It wasn't Emma.
Dave said:
It was Chris,
It wasn't Alan.
Emma said:
It was Dave,
It was Alan.
Who ate the last slice of cake?