No problem, about using an external var, watch out because it'll keep its value when your function is called more than once, and that'll give you wrong results.

Thanks again for not giving me the answer but pointing me in the right direction.

A little push in the right direction is the way to do it. At least for me.

Because you're doing recursion wrong. See what your code does here: http://www.pythontutor.com/visualize.html#mode=edit

No problem, you can see what the input value is printing it: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#print-input

It is passing all the test case

Not exactly, it passes all the tests until it times out with another one. You also have an infinite loop because you didn't validate the input values as per instructions.