Given the task definition, example input & output, solve the new input case.
Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.
Example: Female snakes incubate eggs inside of their bodies, giving birth to live young of ____ or more.
Output: ten
Snakes give birth to minimum ten young ones so ten is a correct answer.

New input case for you: Skyes are very slow in developing, reaching maturity at about ____ years of age.
Output:
three