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.

Input: Consider Input: Fact: damming a river can cause a lake to form.

Output: beaver dam.


Input: Consider Input: Fact: boiling means change from a liquid into a gas by adding heat energy.

Output: boiling change.


Input: Consider Input: Fact: an animal requires nutrients for survival.


Output: animal nutrients.