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

Ex Input:
Which Nation does Aston Villa Goalkeeper Brad Guzan represent?

Ex Output:
brad guzan


Ex Input:
Mar Chiquita (Cordoba) is the largest natural salt lake in which South American country?

Ex Output:
mar chiquita lake


Ex Input:
Who composed Air on the G String?

Ex Output:

air on the g string