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: Who won the 2011 Booker Prize for 'The Sense of an Ending'?
Example Output: the sense of an ending

Example Input: Also the director of 'Insomnia' and 'The Dark Knight', who directed the 2010 sci-fi film 'Inception'?
Example Output:
the dark knight