instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Brasilia is the capital but which city in Brazil has the largest population?
answer:
brazil


question:
Can you name the final movie directed by Alfred Hitchcock?
answer:
alfred hitchcock


question:
Who wrote and performed the song Rehab that won the 2007 Ivor Novello Award for Best Contemporary Song, and Grammy Awards in 2008 for Record of the Year, Song of the Year, and Best Female Pop Vocal Performance?
answer:

rehab