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

Example Input: In which US state are the Catskill Mountains?
Example Output: catskill mountains

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: What is the official language of Brunei ?
Example Output:
brunei