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: fog is formed by water vapor condensing in the air.

Ex Output:
fog is formed.


Ex Input:
Fact: faulting of rock in Earth 's crust causes earthquakes.

Ex Output:
Earthquakes are shaking.


Ex Input:
Fact: weathering means breaking down rocks from larger whole into smaller pieces by weather.

Ex Output:

freeze thaw weathering.