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.

Example Input: masakuni yamamoto (山本 昌邦, yamamoto masakuni, born april 4, 1958) is a former japanese football player.
Example Output: masakuni yamamoto

Example Input: jujutsu (柔術, jūjutsu) is an ancient japanese martial art.
Example Output: jujutsu

Example Input: a palaestra was a building in ancient greece.
Example Output:
palaestra