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