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

Example Input: The bells were ringing for Chuck Berry when this song made it to No1. His first and only British No. 1. What song?
Example Output: chuck berry

Example Input: Brasilia is the capital but which city in Brazil has the largest population?
Example Output: brazil

Example Input: California is bordered by 3 states, Arizona and Nevada are two name the third,?
Example Output:
california