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: giorgio chiellini (born 14 august 1984) is an italian football player.
Example Output: giorgio chiellini

Example Input: the cyclostomes (or cyclostomata) are the lamprey and hagfish.
Example Output: cyclostome

Example Input: stephen hawking predicted that black holes eject some radiation (energy), even though they normally swallow everything.
Example Output:
stephen hawking