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: Some viruses have an envelope of phospholipids and proteins.

Ex Output:
envelope phospholipids and proteins.


Ex Input:
Fact: phase changes do not change mass.

Ex Output:
Phase changes.


Ex Input:
Fact: Puberty is the period during which humans become sexually mature.

Ex Output:

Puberty.