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.

Ex Input:
ligny-sur-canche is a commune.

Ex Output:
ligny-sur-canche


Ex Input:
an aloha shirt (also known as a hawaiian shirt) is a type of shirt that comes from hawaii.

Ex Output:
aloha shirt


Ex Input:
the mil mi-1 (russian: Мил Ми-1; nato reporting name: hare) is a soviet civilian and military helicopter.

Ex Output:

mil mi-1