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

Example Input: Which group had UK top ten hits in 1987 with 'Sweet Little Mystery' and 'Angel Eyes'?
Example Output: angel eyes

Example Input: Physics. What is the SI unit for amount of substance?
Example Output: amount of substance

Example Input: What is the highest mountain in the Alps?
Example Output:
alps