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:
hop and go is a 1943 looney tunes short movie directed by u.s. corporal norman mccabe and released to movie theaters by rko radio pictures.

Ex Output:
hop and go


Ex Input:
child development refers to biological, psychological and emotional changes that happen in humans between birth and the end of adolescence, at which time the individual goes from dependence to independence.

Ex Output:
child development


Ex Input:
canada day is a national and an official holiday in canada celebrating its anniversary of confederation.

Ex Output:

canada day