like I said, print

I can reproduce it just fine. Just run the same case. You're not running a DIFFERENT case from the one that crashes, are you?

to be fair they say "punctuation marks" .. but you should note that they're not any different from space.

if you think you know where it is then you should find out whether that is the case before you do anything else. don't guess, that doesn't let you narrow things down.

kata description doesn't say anything about those characters. makes no sense to have those in your code.

didn't say debugger. print goes a long way.

Not sure that's much of a question though. That comes with the territory of using an unsafe language. Get out your debugging tools.

Is your function's name calculate or have you changed it to something else?