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