#include <bits/stdc++.h>
using namespace std;

int main() {
	char line[200];
	int n;
	cin >> n;
	cin >> line;
	int out = 0;
	for (int i = 0; i < n - 1; i++) {
		if (line[i] == '(' && line[i + 1] == ')') {
			out++;
			continue;
		}
		if (line[i] == ')' && line[i + 1] == ')') {
			out++;
			continue;
		}		
	}
	cout << out << endl;
	return 0;
}