Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

Example Input: a viola is a musical instrument which is similar to the violin and cello.
Example Output: viola

Example Input: a web hosting service is a type of internet hosting service.
Example Output: web hosting service

Example Input: the division of moore is an australian electoral division in the state of western australia.
Example Output:
division of moore