#include <iostream>

using namespace std;

int main(){

    int n;
    char current, prev;
    int result = 0;
    cin >> n;


    for (int i = 0; i < n; ++i) {
        cin >> current;
        if(i == 0) { //first
        } else {
            if(current == '(' && prev == ')') { // +

            } else if (current == ')' && prev == '(') { // 1
                result += 1;
            } else if (current == ')' && prev == ')') { // + 1
                result += 1;
            }
        }
        prev = current;
    }
    cout << result << endl;
    return 0;
}