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

Ex Input:
Any number divided by itself equals _ , except if that number is zero .

Ex Output:
one


Ex Input:
Normal adults appear to require _ to eight hours of sleep per day on average.

Ex Output:
six


Ex Input:
Gibberellins are diterpenoids derived from four isoprenoid units forming a system of _ rings.

Ex Output:

four