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: Cells contain ____ families of small organic molecules.
Example Output: four

Example Input: Green energy comes in ____ basic forms.
Example Output: two

Example Input: Most linguists organize the African languages into ____ major language families .
Example Output:
four