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.

Input: Consider Input: Yellow fever begins suddenly after an incubation period of three to ____ days.

Output: five


Input: Consider Input: Human feet bear average ____ to six hundreds tons of weight everyday.

Output: five


Input: Consider Input: Most countries start at ____ years old.


Output: eight