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:
ricardo de la espriella toral (born september 5, 1934) is a panamanian politician.
answer:
ricardo de la espriella

question:
yoshihiro uchimura (born 24 august 1984) is a japanese football player.
answer:
yoshihiro uchimura

question:
nightmare disorder, also known as "dream anxiety disorder", is a sleep disorder characterized by frequent nightmares.
answer:
nightmare disorder