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

int main(){
	int n;
	string s;
	cin >> n >> s;
	vector<int> p(n+1, 0), m(n+1, 0);
	for(int i=0; i<n; i++){
		p[i+1] += p[i];
		m[i+1] += m[i];
		if(s[i] == '+') p[i+1]++;
		if(s[i] == '-') m[i+1]++;
	}
	int ans = 0;
	for(int i=0; i<=n; i++){
		ans = max(ans, m[i]+p[n] - p[i] + (s[i] == '0'));
	}
	cout << ans << endl;
}