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:
the wisconsin river is a river in the united states.

Ex Output:
wisconsin river


Ex Input:
various positions is the seventh studio album by leonard cohen, it was released in december 1984 (and february 1985).

Ex Output:
various positions


Ex Input:
chorley is a town in lancashire.

Ex Output:

chorley