#include <bits/stdc++.h>
using namespace std;
int i, i0, n, m, k, pre[200005];
char s[200005];
int main() {
  scanf("%d %s", &n, s);
  for (i = 0; i < n; i++) pre[i] = pre[i - 1] + (s[i] == '#');
  m = pre[n - 1];
  for (i = 0; i < n; i++) m = min(m, pre[i] + n - 1 - pre[n - 1] - i + pre[i]);
  printf("%d\n", m);
  return 0;
}
