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