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 nissan maxima is an automobile produced by nissan motor company in seven generations since 1981.
Example Output: nissan maxima

Example Input: the vickers machine gun (also known as the vickers gun) was a machine gun that was used by the british army from 1912 to 1968.
Example Output: vickers machine gun

Example Input: air jamaica is the national airline of jamaica from kingston, jamaica.
Example Output:
air jamaica