#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
const long long INF = mod * mod;
const int INF_N = 1e+9;
const long double eps = 1e-12;
const long double pi = acos(-1.0);
long long mod_pow(long long a, long long n, long long m) {
  long long res = 1;
  while (n) {
    if (n & 1) res = res * a % m;
    a = a * a % m;
    n >>= 1;
  }
  return res;
}
struct modint {
  long long n;
  modint() : n(0) { ; }
  modint(long long m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod) a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0) a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((long long)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0) return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2) res = res * a;
  return res;
}
long long inv(long long a, long long p) {
  return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
const int max_n = 1 << 18;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b) return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}
using mP = pair<modint, modint>;
int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};
void solve() {
  int N;
  cin >> N;
  string s;
  cin >> s;
  int bl = 0, wr = 0;
  vector<int> bc(N + 1, 0), wc(N + 1, 0);
  for (int i = 0; i < N; i++) {
    if (s[i] == '.') {
      wr = max(wr, i);
      bc[i + 1] = bc[i];
    } else {
      bc[i + 1] = bc[i] + 1;
    }
  }
  reverse((s).begin(), (s).end());
  for (int i = 0; i < N; i++) {
    if (s[i] == '#') {
      bl = max(bl, i);
      wc[i + 1] = wc[i];
    } else {
      wc[i + 1] = wc[i] + 1;
    }
  }
  cout << min(bc[wr + 1], wc[bl + 1]) << endl;
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  solve();
  return 0;
}
