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

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    int N; string S; cin >> N >> S;
    int L = 0;
    while(S[L] != '#') L++;
    vector<pair<char,ll>> v;
    v.push_back({S[0], 1});
    for(int i = 1; i < N; i++) {
        if(v.back().first == S[i]) {
            v.back().second++;
        } else {
            v.push_back({S[i], 1});
        }
    }

    ll ans = 0;
    for(auto [ch, cnt] : v) if(ch == '#') ans = max(ans, cnt);
    cout << ans + N - L - 1 << endl;
}