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: ammonium carbonate, also known as baker's ammonia or sal volatile, is a chemical compound.
Example Output: ammonium carbonate

Example Input: mohamed allalou (born september 28, 1973) is an algerian boxer.
Example Output: mohamed allalou

Example Input: lufengosaurus is a genus of early sauropod dinosaur from the lower jurassic of china.
Example Output:
lufengosaurus