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

using ll = long long;

bool chmin(auto &a, auto b) { return a > b ? a = b, true : false; }
bool chmax(auto &a, auto b) { return a < b ? a = b, true : false; }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n; cin >> n;
    string s; cin >> s;

    vector dp(n, vector<int>(3));
    if(s[0] == '-') dp[0][0] = 1;
    else if(s[0] == '0') dp[0][1] = 1;
    else dp[0][2] = 1;
    for(int i=1; i<n; ++i) {
        if(s[i] == '-') {
            dp[i][0] = dp[i-1][0] + 1;
            dp[i][1] = dp[i-1][1];
            dp[i][2] = dp[i-1][2];
        } else if(s[i] == '0') {
            dp[i][0] = dp[i-1][0];
            dp[i][1] = max(dp[i-1][0] + 1, dp[i-1][1]);
            dp[i][2] = dp[i-1][2];
        } else {
            dp[i][0] = dp[i-1][0];
            dp[i][1] = dp[i-1][1];
            dp[i][2] = max({dp[i-1][0], dp[i-1][1], dp[i-1][2]}) + 1;
        }
    }
    cout << max({dp[n-1][0], dp[n-1][1], dp[n-1][2]}) << endl;
}