#include <bits/stdc++.h>

using namespace std;

using ll = long long;

ll eval(string& s, int &i) {
    ll prod = 0;
    for (;; ++i)
    {
        if (s[i] == '(' && prod == 0)
        {
            prod = 1;
        }
        if (s[i] == ')')
        {
            return prod + 1;
        }
        if (s[i] == '(')
        {
            ++i;
            prod *= eval(s, i);
        }
    }
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n;
    string s;
    cin >> n >> s;
    int i = 1;
    s = "(" + s + ")";
    cout << eval(s, i) - 1 << '\n';
    return 0;
}