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: Gene flow occurs when individuals move into or out of a population.

Ex Output:
Gene flow.


Ex Input:
Fact: Zooplankton are tiny animals that feed on phytoplankton.

Ex Output:
Zooplankton.


Ex Input:
Fact: adding salt to a liquid decreases the melting point of that liquid.

Ex Output:

add salt density.