It won't work. With a finite number of ads you can just store all the answers in a database. Captchas only work because they can be generated on the fly and don

It won't work. With a finite number of ads you can just store all the answers in a database. Captchas only work because they can be generated on the fly and don't need to be re-used. Reusing a captcha is like reusing a one-time pad or a condom. Just asking to be broken.