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:
zhejiangopterus is a pterosaur that was found in china.

Ex Output:
zhejiangopterus


Ex Input:
metal gear is an action-adventure stealth video game franchise made by konami.

Ex Output:
metal gear


Ex Input:
ayyavazhi (, "path of the father"), is a religion with one god that started in south india in the middle of the 19th century.

Ex Output:

ayyavazhi