#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  string S;
  cin >> S;
  int l = -1;
  int r;
  int cnt = 0;
  for (int i = 0; i < N; i++){
    if (S[i] == '#'){
      if (l == -1){
        l = i;
      }
      r = i;
      cnt++;
    }
  }
  cout << max(N - l, cnt * 2 - 1 + (N - 1 - r)) << endl;
}