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: Natural ytterbium is a mixture of ____ stable isotopes, with seven other unstable isotopes known.
Example Output: seven

Example Input: Sexual maturity is reached within ____ to four years.
Example Output: two

Example Input: Male bears take five or ____ years to mature.
Example Output:
six