#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int INT_INF = (int)(2e9);
const ll LL_INF = (ll)(2e18);
inline void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
};
template <typename T, typename S>
inline ostream& operator<<(ostream& os, const pair<T, S> p) {
  cout << "[" << p.first << ";" << p.second << "]";
  return os;
}
template <typename T, typename S>
inline ostream& operator<<(ostream& os, const map<T, S> p) {
  for (auto el : p) cout << "[" << el.first << ";" << el.second << "]";
  return os;
}
template <typename T>
inline ostream& operator<<(ostream& os, const vector<T>& v) {
  for (auto el : v) cout << el << " ";
  return os;
}
template <typename T>
inline ostream& operator<<(ostream& os, const deque<T>& v) {
  for (auto el : v) cout << el << " ";
  return os;
}
template <typename T>
inline ostream& operator<<(ostream& os, const set<T>& v) {
  for (auto el : v) cout << el << " ";
  return os;
}
template <typename T>
inline vector<T> fetch_vec(int sz) {
  vector<T> ret(sz);
  for (auto& elem : ret) cin >> elem;
  return ret;
}
int N;
string S;
void input() {
  fast_io();
  cin >> N >> S;
}
int WAsolve() {
  string T = S;
  string V = S;
  int le = 0, ri = N - 1;
  int ans = 0;
  while (ri - le > 0) {
    while (V[ri] == '#') ri--;
    while (V[le] == '.') le++;
    if (ri <= le) break;
    if (V[le] == '#' && V[ri] == '.') {
      int L = 0, R = 0;
      while (V[le + L] == '#') L++;
      while (V[ri - R] == '.') R++;
      if (L < R) {
        ans += L;
        le += L;
      } else {
        ans += R;
        ri -= R;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
vector<int> AS;
int cal(int i, int j, char c) {
  if (c == '#') return AS[j + 1] - AS[i];
  return (j - i + 1) - (AS[j + 1] - AS[i]);
}
int solve() {
  int ans = N + 1;
  AS.assign(N + 1, 0);
  for (int i = 0; i < N; i++) {
    AS[i + 1] = AS[i] + (S[i] == '#');
  }
  for (int i = 0; i < N; i++) {
    int tmp = cal(0, i, '#') + cal(i + 1, N - 1, '.');
    ans = min(ans, tmp);
  }
  cout << ans << endl;
  return 0;
}
int main() {
  input();
  solve();
  return 0;
}
