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: survivor series (2016) was a wrestling pay-per-view (ppv) made by wwe for the "raw" and "smackdown live" brands.
Example Output: survivor series (2016)

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: nafisa ali (born 18 january 1957) is an indian bengali actress, activist and politician.
Example Output:
nafisa ali