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

Input: Consider Input: Ozone is a form of oxygen in which the molecule contains _ atoms instead of two.

Output: three


Input: Consider Input: Transitional milk is secreted between about four days and _ days postpartum.

Output: ten


Input: Consider Input: Piano duets are for two players at _ piano.


Output: one