#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  cin >> n >> s;
  s += 'Y';
  vector<int> wh(n + 1, 0), bl(n + 1, 0);
  int co = 0;
  for (int i = 1; i < n + 1; i++) {
    if (s[i] == '#') co++;
    wh[i] = co;
  }
  co = 0;
  for (int i = n - 1; i >= 0; i--) {
    if (s[i] == '.') co++;
    bl[i] = co;
  }
  int ans = 200000;
  for (int i = 0; i < n + 1; i++) {
    ans = min(ans, wh[i] + bl[i]);
  }
  cout << ans << endl;
}
