#include <iostream>

using namespace std;

using ull = unsigned long long;

void solve() {
    ull n;
    cin >> n;

    std::string buffer;
    buffer.reserve(n*5);
    char last = 0;
    ull sum = 0;
    for (ull i = 0; i < n; i++){
        char c;
        cin >> c;

        if (last == '(' && c == ')'){
            ++sum;
        } else if (last == ')' && c == ')'){
            ++sum;
        }

        last = c;
    }
    cout << sum << std::endl;
}

int main() {
    cin.sync_with_stdio(false);
    cin.tie(0);

    solve();

    return 0;
}