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: Amphibians have permeable skin that easily absorbs substances from the environment.

Ex Output:
Amphibians skin.


Ex Input:
Fact: Specialization occurs when competing species evolve different adaptations.

Ex Output:
adaptations.


Ex Input:
Fact: when a metal rusts , that metal becomes orange on the surface.

Ex Output:

metal iron.