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:
varicose veins are a condition in which the veins in the leg area have become enlarged.

Ex Output:
varicose veins


Ex Input:
a rearguard is a part of a military force that protects the main force from attack from the rear.

Ex Output:
rearguard


Ex Input:
martha maria yeardley smith (born july 3, 1964) is an emmy award-winning american actress, comedian and writer.

Ex Output:

yeardley smith