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

Example Input: Which Chuck Berry song is performed by Marty McFly at the end of the film Back to the Future?
Example Output: back to the future

Example Input: Which group had UK top ten hits in 1987 with 'Sweet Little Mystery' and 'Angel Eyes'?
Example Output: angel eyes

Example Input: Bigwig, Fiver and Hazel are the main characters in which 1972 novel?
Example Output:
fiver