Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Example Input: Mr Barkis, Edward Murdstone and Tommy Traddles are all characters in which Charles Dickens novel?
Example Output: charles dickens

Example Input: Who was re-elected Prime Minister of Canada in May 2011?
Example Output: prime minister of canada

Example Input: Which ex-World Heavyweight Champion boxer signed up for Celebrity Big Brother 2014?
Example Output:
celebrity big brother