#include <iostream>
#include <set>

using namespace std;

int main() {
    int nmbOfChars;
    cin >> nmbOfChars;

    int sum = 0;
    char lastChar = '_';
    for (; nmbOfChars > 0; --nmbOfChars) {
        char currentChar;
        cin >> currentChar;

        if (lastChar == '(' && currentChar == ')') {
            sum++;
        }
        if (lastChar == ')' && currentChar == ')') {
            sum++;
        }
        lastChar = currentChar;
    }
    cout << sum << endl;

    return 0;
}