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

Ex Input:
Who sang the theme tune to the James Bond film Die Another Day?

Ex Output:
die another day

Ex Input:
Where is David Cameron's Oxfordshire constituency?

Ex Output:
david cameron

Ex Input:
The River Yarra flows through which city?

Ex Output:
yarra river