#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 0
#define dbgn(...) 0
#endif

void solve() {
    int n;
    cin >> n;
    string s;
    cin >> s;

    vector<int> np(n + 1, 0);
    for (int i = 0; i < n; i++) {
        np[i + 1] = np[i] + (s[i] == '-' ? 1 : 0);
    }

    vector<int> ps(n + 1, 0);
    for (int i = n - 1; i >= 0; i--) {
        ps[i] = ps[i + 1] + (s[i] == '+' ? 1 : 0);
    }

    int ans = 0;

    for (int i = 0; i <= n; i++) {
        int c = np[i] + ps[i];
        if (c > ans) {
            ans = c;
        }
    }

    for (int i = 0; i < n; i++) {
        if (s[i] == '0') {
            int c = np[i] + 1 + ps[i + 1];
            if (c > ans) {
                ans = c;
            }
        }
    }

    cout << ans << '\n';
}

int32_t main() {
    cin.tie(0)->sync_with_stdio(0);
    solve();
    return 0;
}