#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using P = pair<int, int>;
using llP = pair<ll, ll>;
using DoP = pair<double, double>;
const int di[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int dj[] = {1, 0, -1, 0, 1, -1, 1, -1};
const int INF = 1 << 30;
const ll INF64 = 1ll << 55;
const int mod = 1000000007;
template <class T>
inline bool chmin(T &a, const T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T &a, const T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline void line_out(const vector<T> vec) {
  int n = ((int)(vec).size());
  for (int i = 0; i < n; ++i) {
    cout << vec[i];
    if (i < n - 1) cout << " ";
  }
  cout << endl;
  return;
}
struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod) x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint &operator++() {
    if ((x += 1) >= mod) x -= mod;
    return *this;
  }
  mint &operator--() {
    if ((x += mod - 1) >= mod) x -= mod;
    return *this;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) a *= *this;
    return a;
  }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};
int main() {
  int n;
  string s;
  cin >> n >> s;
  int b = 0, w = 0;
  int i = 0;
  while (i < n && s[i] == '.') ++i;
  for (i; i < n; ++i) {
    if (s[i] == '.') ++b;
  }
  reverse((s).begin(), (s).end());
  i = 0;
  while (i < n && s[i] == '#') ++i;
  for (i; i < n; ++i) {
    if (s[i] == '#') ++w;
  }
  cout << min(b, w) << endl;
}
