#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; 
	cin >> n; 
	string str; 
	cin >> str; 
	vector<vector<int>> dp(n + 1, vector<int> (3)); 
	for(int i = 0; i < n; i++){
		dp[i + 1] = dp[i]; 
		if(str[i] == '+'){
			dp[i + 1][2] = max(dp[i][1] + 1, dp[i][2] + 1); 
		}
		if(str[i] == '0'){
			dp[i + 1][1] = dp[i][0] + 1; 
		}
		if(str[i] == '-'){
			dp[i + 1][0] = dp[i][0] + 1; 
		}
	}
	cout << max({dp[n][0], dp[n][1], dp[n][2]}) << '\n'; 
}

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