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

Example Input: Which major river has its source at the confluence of the rivers Brigach and Breg in the Black Forest?
Example Output: breg

Example Input: What name is given to the murder of 7 people as part of a Prohibition Era conflict between the South Side Italian gang led by Al Capone and the North Side Irish gang led by Bugs Moran in Chicago, Illinois, in 1929?
Example Output: bugs moran

Example Input: Which famous novel was written in 1877 by Anna Sewell as a protest against cruelty to horses?
Example Output:
anna sewell