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:
aesthetics is a branch of philosophy.

Ex Output:
aesthetics

Ex Input:
prospecting is the physical search for minerals, fossils, precious metals or mineral specimens.

Ex Output:
prospecting