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

Example Input: What was Casanova's occupation at the time of is death?
Example Output: giacomo casanova

Example Input: July 1938 saw the first ascent of the North Face of which Alpine mountain?
Example Output: alps

Example Input: Who teamed up with Rihanna on the 2012 track Birthday Cake Chris Brown, Jay Sean, Nelly, Usher?
Example Output:
birthday cake