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]: yoshikazu goto (後藤 義一, goto yoshikazu, born february 20, 1964) is a japanese professional athlete.
[EX A]: yoshikazu goto

[EX Q]: a rearguard is a part of a military force that protects the main force from attack from the rear.
[EX A]: rearguard

[EX Q]: internet relay chat (irc) is a chat system on the internet.
[EX A]:
internet relay chat