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

Input: Consider Input: Puppies can start vaccinations at _ weeks.

Output: six


Input: Consider Input: Disruptive selection can lead to _ new species.

Output: two


Input: Consider Input: Raptors have acute hearing and vision, which is estimated to be _ to ten times that of humans.


Output: eight