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: Tin exists in ____ allotropic forms.
Example Output: three

Example Input: Spermatogenesis creates ____ sperm of equal size.
Example Output: four

Example Input: Modern scientists recognize ____ main subclasses of prairie in Illinois.
Example Output:
six