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.

Input: Consider Input: Fact: when a river floods , that river deposits soil in flood plains.

Output: flood cause.


Input: Consider Input: Fact: Bile reduces the acidity of food entering from the highly acidic stomach.

Output: acid reduction.


Input: Consider Input: Fact: being burried under soil and mud changes peat into coal through extreme heat and pressure in a swamp over a long period of time.


Output: coal heat peat.