#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  int flag1 = 0, flag2 = 0;
  string s;
  string black, white;
  cin >> n >> s;
  long long count1 = 0, count2 = 0;
  black = s;
  white = s;
  for (long long i = 0; i < n - 1; i++) {
    if (flag1 == 0) {
      if (black.at(i) == '#') {
        flag1 = 1;
      }
    } else {
      if (black.at(i) == '.') {
        count1++;
      }
    }
  }
  for (long long i = n - 1; i > 0; i--) {
    if (flag2 == 0) {
      if (white.at(i) == '.') {
        flag2 = 1;
      }
    } else {
      if (white.at(i) == '#') {
        count2++;
      }
    }
  }
  if (count1 < count2) {
    cout << count1 << endl;
  } else {
    cout << count2 << endl;
  }
}
