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.

Example Input: Fact: Gene flow occurs when individuals move into or out of a population.
Example Output: Gene flow.

Example Input: Fact: animals require water for survival.
Example Output: animal duck.

Example Input: Fact: electricity is used as an energy source by electrical devices.
Example Output:
device phone.