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

Example Input: What is the name of the co-founder of Apple Computers who died in October 2011?
Example Output: apple inc.

Example Input: Which river begins in the Rocky Mountains in south-west Colorado, crosses New Mexico and forms the border between Mexico and the USA before reaching the Gulf of Mexico?
Example Output: new mexico

Example Input: Which artist collaborated with architects Herzog & de Meuron as consultant in building the Beijing National Stadium for the 2008 Olympics?
Example Output:
beijing national stadium