#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<long long>;
using sll = set<long long>;
template <typename T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <typename T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <typename T>
map<T, T> primeFactor(T n) {
  map<T, T> res;
  for (T i = 2; i * i <= n; ++i) {
    while (n % i == 0) {
      res[i]++;
      n /= i;
    }
  }
  if (n != 1) res[n] = 1;
  return res;
}
template <typename T>
bool IsPrimeNumber(T num) {
  if (num <= 2)
    return true;
  else if (num % 2 == 0)
    return false;
  double sqrtNum = sqrt(num);
  for (int i = 3; i <= sqrtNum; i += 2) {
    if (num % i == 0) {
      return false;
    }
  }
  return true;
}
long long modinv(long long a, long long m) {
  long long b = m, u = 1, v = 0;
  while (b) {
    long long t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  u %= m;
  if (u < 0) u += m;
  return u;
}
int main() {
  ll n, ansA = 0, ansB = 0;
  string s;
  bool flgA = false;
  bool flgB = false;
  cin >> n;
  cin >> s;
  for (ll i = 0; i < n; i++) {
    if (flgA) {
      if (s[i] == '.') {
        ansA++;
      }
    } else {
      if (s[i] == '#') {
        flgA = true;
      }
    }
    if (flgB) {
      if (s[n - i - 1] == '#') {
        ansB++;
      }
    } else {
      if (s[n - i - 1] == '.') {
        flgB = true;
      }
    }
  }
  cout << min(ansA, ansB) << '\n';
  return 0;
}
