#include <iostream>


int main() {

    int num;
    std::cin >> num;
    char prev, curr;
    std::cin >> prev;
    size_t res = 0;
    for (int i = 1 ; i < num ; i++){
        std::cin >> curr;
        if ((prev == '('&& curr == ')') || (prev == ')' && curr == ')')) {
            res++;
        }
        prev = curr;
    }

    std::cout <<res << std::endl;



    return 0;


}