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: love hina is a japanese manga.
Example Output: love hina

Example Input: nickel creek was an american acoustic musical group.
Example Output: nickel creek

Example Input: the word longevity means "long life", or "life expectancy".
Example Output:
longevity