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 king of fighters '94 is a 1994 fighting game released by snk for the neo geo arcade and home consoles.

Ex Output:
the king of fighters


Ex Input:
rsgc1 is a massive young open star cluster in the milky way galaxy.

Ex Output:
rsgc1


Ex Input:
nabonga is a 1943 giant gorilla movie starring buster crabbe and julie london.

Ex Output:

nabonga