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.

Example Input: Fact: the number of rings in a tree trunk can be used to estimate the age of the tree.
Example Output: age of tree forest ring.

Example Input: Fact: Cells are programmed to divide only a set number of times.
Example Output: Cells divide.

Example Input: Fact: Menopause occurs when menstruation stops occurring, usually in middle adulthood.
Example Output:
Menopause.