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

Input: Consider Input: Retinoic acid regulates oral epithelial differentiation by _ mechanisms.

Output: two


Input: Consider Input: Nymphs feed for five to _ weeks before entering the adult stage.

Output: eight


Input: Consider Input: Banks merge and change their names at least every once every _ year.


Output: five