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:
mariner 10 was a robotic nasa space probe.

Ex Output:
mariner 10


Ex Input:
absolute truth is something that is true at all times and in all places.

Ex Output:
absolute truth


Ex Input:
wayland, massachusetts is a town in massachusetts, united states.

Ex Output:

wayland, massachusetts