#include <bits/stdc++.h>
using ll = long long;
using namespace std;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
template <class T>
inline bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int main() {
  cin.tie(0), ios::sync_with_stdio(false);
  int n;
  cin >> n;
  string s;
  cin >> s;
  vector<int> b(n + 1), w(n + 1);
  for (int i = 0; i < int(n); i++) {
    if (s[i] == '#') b[i]++;
    b[i + 1] += b[i];
  }
  for (int i = n; 0 < i; i--) {
    if (s[i] == '.') w[i]++;
    w[i - 1] += w[i];
  }
  int ans = (1 << 30) - 1;
  for (int i = 0; i < int(n); i++) chmin(ans, w[i + 1] + b[i]);
  cout << ans;
  cout << "\n";
  return 0;
}
