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: the bighorn sheep ("ovis canadensis") is a species of sheep.
Example Output: bighorn sheep

Example Input: capellen is a town in the commune of mamer, in south-western luxembourg, 12 km west of luxembourg city.
Example Output: capellen

Example Input: peanut butter is a type of moist paste that is made of crushed roasted peanuts.
Example Output:
peanut butter