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: a delta is formed by deposition of sediment at the mouth of a river by water fanning out.

Ex Output:
delta greek.


Ex Input:
Fact: All plants have a characteristic life cycle that includes alternation of generations.

Ex Output:
alternation generations.


Ex Input:
Fact: a ship is used for moving people across bodies of water.

Ex Output:

across bodies of water.