#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  string s;
  int n;
  cin >> n >> s;
  int count11 = 0, count12 = 0, count21 = 0, count22 = 0;
  for (int i = 0; i < n; i++) {
    if (count11 == 0) {
      if (s[i] == '#') {
        count11 = 1;
        count22++;
      }
    } else {
      if (s[i] == '.') count21++;
      if (s[i] == '#') count22++;
    }
  }
  if (count22 > count21)
    cout << count21 << endl;
  else
    cout << count22 << endl;
}
