#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
constexpr int INF = 1000000001;
constexpr ll mod = 1000000007;
constexpr double PI = 3.1415926535897932;
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
inline void init() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
int main() {
  init();
  int N;
  cin >> N;
  string s;
  cin >> s;
  int ans = INF;
  int cnt = 0;
  bool appear = false;
  for (int(i) = (0); (i) < (N); ++(i)) {
    if (s[i] == '#') {
      appear = true;
    } else if (appear)
      ++cnt;
  }
  chmin(ans, cnt);
  cnt = 0;
  appear = false;
  for (int(i) = (N)-1; (i) >= (0); --(i)) {
    if (s[i] == '.') {
      appear = true;
    } else if (appear)
      ++cnt;
  }
  chmin(ans, cnt);
  cout << ans << "\n";
  return 0;
}
