#include <bits/stdc++.h>

using namespace std;

#define ss second
#define ff first
#define p_b push_back
#define endl "\n"

#ifndef LOCAL
    #define cerr if(0)cerr
#endif // LOCAL


typedef long long ll;
typedef long double ld;

const ll INF = 9223372036854775807;
const ll INFINT = 2147483647;
const int N = 1000006;
const int NN = 1006;
const int MOD = 1000000007;

void DIE(string s) {
    cout << s << endl;
    exit(0);
}

void DIE(ll x) {
    cout << x << endl;
    exit (0);
}

void DIE(int x) {
    cout << x << endl;
    exit(0);
}

void YES() {
    DIE("YES");
}

void Yes() {
    DIE("Yes");
}

void yes() {
    DIE("yes");
}

void NO() {
    DIE("NO");
}

void No() {
    DIE("No");
}

void no() {
    DIE("no");
}
/////////////////
// Write below //
/////////////////

int main () {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef LOCAL
    freopen ("input.txt", "r", stdin);freopen ("output.txt", "w", stdout);
#else
    //freopen ("input.txt", "r", stdin);freopen ("output.txt", "w", stdout);
    //freopen ("mole.in", "r", stdin);freopen ("mole.out", "w", stdout);
#endif // LOCAL
    int n;
    cin >> n;
    n <<= 1;
    string s;
    cin >> s;
    int ans = 0;
    int bal = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == '(') bal++;
        else bal--;
        if (bal < 0) {
            bal += 2;
            ans++;
        }
    }
    //cerr << ans << ' ' << bal << endl;
    cout << ans + bal / 2;
}
/////////////////
// Write above //
/////////////////