#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;
	string s;
	cin >> n >> s;
	vector<int> seq;
	for(int i = 0; i < n; i++) {
		if (s[i] == '-') {
			seq.push_back(-1e8 - i);
		} 
		else if (s[i] == '0') {
			seq.push_back(0); 
		} 
		else if (s[i] == '+') {
			seq.push_back(1e8 + i); 
		}
	}
	vector<int> lis;
	for(int x : seq) {
		auto it = upper_bound(lis.begin(), lis.end(), x);
		if (it == lis.end()) lis.push_back(x);
		else *it = x;
	}
	cout << lis.size() << '\n';
}

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