#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  int black[100002] = {};
  int n_black = 0;
  string S;
  cin >> N >> S;
  for (int i = 1; i <= N; i++) {
    black[i] = black[i - 1];
    if (S[i - 1] == '#') black[i]++;
  }
  n_black = black[N];
  int ans = 2e5 + 1;
  for (int i = 0; i <= N; i++) {
    ans = min(ans, black[i] + (N - i) - (n_black - black[i]));
  }
  cout << ans << endl;
  return 0;
}
