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 australian music prize (the amp) is a yearly award for an australian band or solo artist.
Example Output: australian music prize

Example Input: a hamburger is a type of sandwich with cooked ground meat between the two halves of a bun.
Example Output: hamburger

Example Input: the tokyo subway sarin attack (subway sarin incident (地下鉄サリン事件, chikatetsu sarin jiken) was an act of domestic terrorism on 20 march 1995, in tokyo, japan, by members of the cult movement aum shinrikyo.
Example Output:
tokyo subway sarin attack