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 vektor r4 is a south african assault rifle.

Ex Output:
vektor r4


Ex Input:
silliness is when a person acts like a fool, or shows a lack of good sense or judgment.

Ex Output:
silliness


Ex Input:
the gates of the forest is a book written by nobel peace prize-winning author elie wiesel.

Ex Output:

the gates of the forest