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

Ex Input:
Flatworms exhibit _ forms of life styles, free-living and parasitic.

Ex Output:
two


Ex Input:
World population continues to rise, even as a few countries move toward _ growth.

Ex Output:
zero


Ex Input:
Ozone is a very yin gas made up of _ atoms of oxygen.

Ex Output:

three