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: Hydrogen bonds cause water to expand when it freezes.
Example Output: freezes.

Example Input: Fact: Algae play significant roles as producers in aquatic ecosystems.
Example Output: Algae.

Example Input: Fact: a stove is used for cooking by generating heat.
Example Output:
a stove is used to cook food.