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: Most organ systems are operational in the fetus by ____ to six months.
Example Output: four

Example Input: Human gestation is divided into three trimesters of ____ months each.
Example Output: three

Example Input: Maxillary molars have two buccal cusps and ____ lingual cusps.
Example Output:
two