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: eating something that contains pollutants has a negative impact on an organism 's survival.
Example Output: organic food pollutants.

Example Input: Fact: optical tools are used for observing materials up close.
Example Output: materials.

Example Input: Fact: boulders are formed by glaciers melting sometimes.
Example Output:
boulders glaciers.