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

Input: Consider Input: What's the name of Doctor Who's home planet ?

Output: doctor who


Input: Consider Input: Aldebaran is the brightest star in which constellation?

Output: aldebaran


Input: Consider Input: Who starred in the films: The Gold Rush, City Lights & Modern Times?


Output: the gold rush