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

Ex Input:
Gerbils get reproductive when they reach sexual maturity at the age of _ months.

Ex Output:
three


Ex Input:
Digoxin works in _ ways.

Ex Output:
two


Ex Input:
Natural ytterbium is a mixture of seven stable isotopes, with _ other unstable isotopes known.

Ex Output:

seven