#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  cin >> n >> s;
  int i, a = 0, counta = 0, b = 0, countb = 0;
  for (i = 0; i < s.size(); i++) {
    if (s.at(i) == '#') {
      a = i;
      break;
    }
  }
  for (i = a; i < s.size(); i++) {
    if (s.at(i) == '.') {
      counta++;
    }
  }
  for (i = s.size() - 1; i >= 0; i--) {
    if (s.at(i) == '.') {
      b = i;
      break;
    }
  }
  for (i = b; i >= 0; i--) {
    if (s.at(i) == '#') {
      countb++;
    }
  }
  int ans;
  ans = min(counta, countb);
  cout << ans << endl;
}
