In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Ex Input:
Fact: Most ecosystems get energy from sunlight.

Ex Output:
ecosystem habitat.


Ex Input:
Fact: living things all require energy for survival.

Ex Output:
energy food.


Ex Input:
Fact: Mollusks have a circulatory system with one or two hearts that pump blood.

Ex Output:

Mollusks are snails.