In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Input: Consider Input: Induction also operates early in development, even before the _ layered embryo forms.

Output: three


Input: Consider Input: Crustaceans have _ major body parts .

Output: three


Input: Consider Input: Reverse osmosis uses three to ten gallons of water to produce _ gallon of drinking water.


Output: one