In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Ex Input:
Pure water contains _ ions and is therefore a nonconductor .

Ex Output:
no


Ex Input:
Gravity is the weakest of all _ forces but unlike the others it has an unlimited range.

Ex Output:
four


Ex Input:
Females like to care for three to _ babies at a time because one cub is a waste of time.

Ex Output:

four