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 moirai(the fates) were the three goddesses of destiny in greek mythology.

Ex Output:
moirai


Ex Input:
tactopods are members of a proposed clade of ecdysozoans called tactopoda.

Ex Output:
tactopoda


Ex Input:
cumulative voting is a system for doing an election.

Ex Output:

cumulative voting