#include <bits/stdc++.h>
using namespace std;
long long gcd(long long x, long long y) { return y ? gcd(y, x % y) : x; }
long long MOD = 1000000007;
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;
}
const int MAX = 510000;
long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}
long long COM(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main() {
  int ans = 0;
  int N;
  cin >> N;
  string S;
  cin >> S;
  int state = 0;
  int b = 0;
  int w = 0;
  for (int i = 0; i < N; i++) {
    if (S[i] == '.') {
      if (state == 1) {
        w++;
      }
    }
    if (S[i] == '#') {
      b++;
      state = 1;
    }
  }
  ans = min(w, b);
  cout << ans << endl;
}
