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 title of the four-episode special of 'Doctor Who', made for the Red Nose Day telethon in the UK, broadcast in March 1999?
Example Output: doctor who

Example Input: Which Bob Dylan song begins You got a lotta nerveTo say you are my friend. When I was down, You just stood there grinning?
Example Output: bob dylan

Example Input: Brian Johnson is the singer with which 'hard-rock' band founded in 1973 by brothers Malcolm and Angus Young?
Example Output:
angus young