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 Q]: tuff (from italian "tufo") is a type of rock produced by the eruption of volcanoes.
[EX A]: tuff

[EX Q]: the long-beaked echidnas make up one of the two genera (genus zaglossus) of echidna.
[EX A]: long-beaked echidna

[EX Q]: satoshi horinouchi (born 26 october 1979) is a japanese football player.
[EX A]:
satoshi horinouchi