#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
using ll = long long;
template <class T>
using V = vector<T>;
const ll inf = (1e18);
const ll mod = 1000000007;
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
struct __INIT {
  __INIT() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
  }
} __init;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
ll dp[200005];
int main() {
  for (int i = 0; i < 200005; i++) dp[i] = inf;
  dp[0] = 0;
  int n;
  cin >> n;
  string s, cp = {};
  cin >> s;
  reverse((s).begin(), (s).end());
  for (int i = 0; i < n; i++) {
    if (cp.size() == 0 && s[i] == '#') continue;
    cp.push_back(s[i]);
  }
  reverse((cp).begin(), (cp).end());
  s.clear();
  for (int i = 0; i < cp.size(); i++) {
    if (s.size() == 0 && cp[i] == '.') continue;
    s.push_back(cp[i]);
  }
  n = s.size();
  V<int> cnt(2, 0);
  for (int i = 0; i < n; i++) {
    cnt[(s[i] == '.')]++;
  }
  cout << min(cnt[0], cnt[1]) << endl;
}
