#include <bits/stdc++.h>

using namespace std;
using ll = long long;

string s;

pair<int, ll> parse(int i) {
	ll v = 1;
	bool hap = false;
	while(s[i] == '(') {
		hap = true;
		++i;
		auto p = parse(i);
		i = p.first;
		v *= p.second;
	}
	if(hap) v += 1;
	//cerr << v << '\n';
	return {i+1, v};
}


int main() {
	int n;
	cin >> n;
	cin >> s;
	cout << parse(0).second-1 << '\n';

	return 0;
}