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: bothnian bay (; ) is a bay in the northest of the gulf of bothnia.
Example Output: bothnian bay

Example Input: affringues is a commune.
Example Output: affringues

Example Input: secession in the united states refers mainly to state secession.
Example Output:
secession in the united states