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:
nelsan ellis (november 30, 1977 – july 8, 2017) was an american actor and playwright.

Ex Output:
nelsan ellis


Ex Input:
plankton are drifting organisms that live in the surface layers of the ocean.

Ex Output:
plankton


Ex Input:
maracaibo is a city in northwestern venezuela.

Ex Output:

maracaibo