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 sonata is a piece of music for one instrument or one instrument with another instrument accompanying.
Example Output: sonata

Example Input: pablo escobar and his brother's school once sent them home because they had no shoes and no money to buy them.
Example Output: pablo escobar

Example Input: northern ontario is a geographic and administrative region of the canadian province of ontario.
Example Output:
northern ontario