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: Pathologists study four to ____ years after medical school and their postgraduate training.
Example Output: five

Example Input: Some clouds are so thick and dense that ____ stars can shine through.
Example Output: no

Example Input: African lungfishes possess ____ lungs and are obligate air-breathers.
Example Output:
two