#include <iostream>
#include <vector>
using namespace std;

template<typename T>
void print(const T t, bool ln = true) {
    cout << t;
    if (ln) {
        cout << '\n';
    } else {
        cout << ' ';
    }
}

template<typename T>
void printv(const vector<T> &v) {
    for (int i = 0; i < (int)v.size(); i++) {
        print(v[i], false);
    }
    cout << '\n';
}

template<typename T>
void printvv(const vector<vector<T>> &vv) {
    for (int i = 0; i < (int)vv.size(); i++) {
        vprint(vv[i]);
    }
}

void solve() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    vector<int> normal(n + 1, 1), reverse(n + 1, 1);
    for (int i = 0; i < n; i++) {
        if (s[i] == '+') {
            reverse[i + 1] = -1;
        } else if (s[i] == '-') {
            normal[i + 1] = -1;
        }
        normal[i + 1] += normal[i];
        reverse[i + 1] += reverse[i];
    }

    int now = 0, l = 0, cnt = 0;
    while (l < n) {
        int r = -1;
        for (int i = l + 1; i <= n; i++) {
            if (now + normal[i] - normal[l] < 0) {
                r = i;
                break;
            }
        }

        if (r == -1) {
            break;
        }

        cnt++;
        int mx = -1;
        for (int m = l + 1; m < r; m++) {
            if (mx < now + (normal[m] - normal[l]) + (reverse[r] - reverse[m])) {
                mx = now + (normal[m] - normal[l]) + (reverse[r] - reverse[m]);
            }
        }

        now = mx;
        l = r;
        for (r++; r <= n; r++) {
            if (now + (reverse[r] - reverse[l]) < 0) {
                break;
            }
        }

        if (r == n + 1) {
            break;
        }

        mx = -1;
        for (int m = l + 1; m < r; m++) {
            if (mx < now + (reverse[m] - reverse[l]) + (normal[r] - normal[m])) {
                mx = now + (reverse[m] - reverse[l]) + (normal[r] - normal[m]);
            }
        }
        now = mx;
        l = r;
    }

    cout << cnt << '\n';
}

int main() {
    int q = 1;
    // cin >> q;
    while (q--) {
        solve();
    }
}