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 wisconsin river is a river in the united states.
Example Output: wisconsin river

Example Input: sonic firestorm is the second studio album by english power metal band dragonforce released through on may 11, 2004.
Example Output: sonic firestorm

Example Input: annastacia palaszczuk (born 25 july 1969) is an australian politician.
Example Output:
annastacia palaszczuk