instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Allopurinol is typically prescribed for which illness?
answer:
allopurinol


question:
Brasilia is the capital but which city in Brazil has the largest population?
answer:
brazil


question:
The bells were ringing for Chuck Berry when this song made it to No1. His first and only British No. 1. What song?
answer:

chuck berry