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.

Ex Input:
Fact: Flowing water can slowly dissolve carbon in sedimentary rock.

Ex Output:
flowing water fall force.


Ex Input:
Fact: Bone is less flexible than cartilage but stronger.

Ex Output:
bone cartilage.


Ex Input:
Fact: hitting an object causes the particles in that object to vibrate.

Ex Output:

gong hit.