#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  string s;
  cin >> n >> s;
  int p = 0, m = 0;
  for (char c : s)
    if (c == '+') ++p;
  int ans = p;
  for (char c : s) {
    if (c == '-') ++m;
    if (c == '+') --p;
    if (c == '0') ans = max(ans, p + m + 1);
    ans = max(ans, p + m);
  }
  cout << ans << '\n';
  return 0;
}