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.

Ex Input:
in 2013, esther peterson was inducted into the us department of labor's hall of honor.

Ex Output:
esther peterson

Ex Input:
zabno (polish: zabno) is a town in poland.

Ex Output:
zabno

Ex Input:
michigan avenue is a major north-south street in chicago.

Ex Output:
michigan avenue