#include <bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin >> n;
	string s;
	cin >> s;
	int c = 0;
	for(int i = 0; i < s.size()-1; ++i) {
		if(s[i] == ')' && s[i+1] == ')')++c;
		if(s[i] == '(' && s[i+1] == ')')++c;
	}
	cout << c << '\n';
	return 0;
}