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

Example input: Who was the first American President?
Example output: president of the united states
Example explanation: The question talks about the president of the USA.
Q: Which artist collaborated with architects Herzog & de Meuron as consultant in building the Beijing National Stadium for the 2008 Olympics?
A:
beijing national stadium