#include <algorithm>
#include <bits/stdc++.h>
using namespace std;

using i32 = int;
using i64 = long long;
#define int i64

signed main() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    vector<int> conv(n);

    int actual = 1;
    for (int i = 0; i < n; i++){
        if (s[i] == '+') {
            conv[i] = actual++;
        }
    }
    actual = -1;
    for (int i = n - 1; i >= 0; i--) {
        if (s[i] == '-') {
            conv[i] = actual--;
        }
    }
    vector<int> vals;
    vals.push_back(conv[0]);
    for (int i = 1; i < n; i++) {
        if (vals.back() < conv[i]) {
            vals.push_back(conv[i]);
            continue;
        }
        int pos = upper_bound(vals.begin(), vals.end(), conv[i]) - vals.begin();
        vals[pos] = conv[i];
    }
    cout << vals.size() << endl;

}