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

Ex 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?

Ex Output:
doctor who


Ex Input:
Who played the character Gene Hunt in the UK TV series 'Life on Mars' and 'Ashes to Ashes'?

Ex Output:
life on mars


Ex Input:
Whose first solo number one single was 'Careless Whisper'?

Ex Output:

careless whisper