#include <bits/stdc++.h>
using namespace std;
int b[200005], w[200005];
int N;
string S;
int main() {
  cin >> N >> S;
  b[0] = 0;
  w[0] = 0;
  for (int i = 0; i < N; ++i) {
    b[i + 1] = b[i] + (S[i] == '.' ? 1 : 0);
    w[i + 1] = w[i] + (S[i] == '#' ? 1 : 0);
  }
  int ans = N;
  for (int i = 0; i <= N; ++i) {
    if (w[i] + (b[N] - b[i]) < ans) ans = b[i] + (w[N] - w[i]);
  }
  cout << ans << endl;
  return 0;
}
