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: Invertebrates are animals that lack a vertebral column, or backbone.
Example Output: Invertebrate.

Example Input: Fact: exercise has a positive impact on a human 's health.
Example Output: Exercise is movement.

Example Input: Fact: Animals may compete for territory, water, food, or mates.
Example Output:
animal competition.