CAPTCHAs are meant to distinguish humans from robots.

One of the cutest types of CAPTCHA is the math challenge: instead of numbers, a tiny arithmetic operation is written out in words, and the human must solve it.

The challenge here is to write code that allows a robot to solve this puzzle.

This kind of simplistic challenge is still proudly used by some modules for a well-known CMS.

In the initial table, the numbers with 8 are misspelled "height", "heighteen" and "heighty", that have a unexpected "h".

Near line 42 you have to check if b is zero, otherwise it prints something like "twenty zero" instead of "twenty".