#include <bits/stdc++.h>
int main(void) {
  int n, cnt1 = 0, cnt2 = 0, f = 0;
  char s[2000000];
  scanf("%d", &n);
  scanf("%s", &s);
  for (int i = 0; i < n; i++) {
    if ((f == 0) && s[i] == '#') f = 1;
    if ((f == 1) && s[i] == '.') cnt1++;
  }
  f = 0;
  for (int i = n - 1; i >= 0; i--) {
    if ((f == 0) && s[i] == '.') f = 1;
    if ((f == 1) && s[i] == '#') cnt2++;
  }
  if (cnt1 < cnt2)
    printf("%d\n", cnt1);
  else
    printf("%d\n", cnt2);
  return 0;
}
