instruction:
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.
question:
norio yoshimizu (吉水 法生, yoshimizu norio, born august 21, 1946) is a former japanese football player.
answer:
norio yoshimizu


question:
a hospital ship is a big boat which is built to cure patients.
answer:
hospital ship


question:
the rouran ruled northern china during the sixteen kingdoms period.
answer:

rouran