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: fukuoka airport (, fukuoka kuko) , formerly known as itazuke air base, is a japanese airport in fukuoka.
Example Output: fukuoka airport

Example Input: the movie producer, martin ransohoff, made a ten-minute documentary promoting her, called "all eyes on sharon tate".
Example Output: sharon tate

Example Input: skin effect is the tendency of an alternating electric current to flow towards the perimeter of a conductor and leave the center part of the conductor without (or barely) any electricity flow.
Example Output:
skin effect