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: Viruses often infect bacteria.
Example Output: bacteria define.

Example Input: Fact: gravity pulls objects towards planets.
Example Output: gravity objects planets.

Example Input: Fact: the Earth being tilted on its axis causes ones side of the Earth to receive less energy from the Sun than the other side.
Example Output:
earth side less energy cold weather.