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:
bobby ryan (born robert shane stevenson; march 17, 1987 in cherry hill, new jersey) is an american professional ice hockey right winger.

Ex Output:
bobby ryan


Ex Input:
troy smith (born july 20, 1984 in cleveland, ohio) is an american football quarterback that most recently played for the omaha nighthawks of the united football league.

Ex Output:
troy smith


Ex Input:
the permian is a geological period which started about 299 million years ago (mya), and ended about 252 mya.

Ex Output:

permian