Hmmmm now I got it. Smart indeed, need to think of that next time. Now it seems so dumb to me. Thanks for the interesting website as well and the quick responses.

I don't get it because ")(" is the same characters as "()" and that returns zero.

akar-0 was trying to help you and he just wrote a cordial message and behaved in a civilised way as should anyone in comment sections.

Seems a little easy for a 5 kyu.

That shouldn't work, because the when you have ")(" in your string, it's invalid, even thought the count is equal to 0.