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

Ex Input:
Which late 17th and early 18th century British architect designed Brighton Pavilion, Marble Arch, and the plan for London's Regents Park?

Ex Output:
royal pavilion

Ex Input:
Mr Barkis, Edward Murdstone and Tommy Traddles are all characters in which Charles Dickens novel?

Ex Output:
charles dickens

Ex Input:
Premiered in 1947 which composer wrote the music for the opera 'Albert Herring'?

Ex Output:
albert herring