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 Input: Mosquitoes live ____ to eight weeks.
Example Output: four

Example Input: Couples spend ____ billion dollars a year on infertility treatments.
Example Output: two

Example Input: Most aviators serve ____ years after they complete their initial flight training.
Example Output:
seven