#include <bits/stdc++.h>
int getNumsInt32(int32_t *buf, int32_t num) {
  int32_t i;
  for (i = 0; i < num; i++) {
    if (scanf("%d", &buf[i]) == EOF) {
      return -1;
    }
  }
  return 0;
}
int main() {
  int32_t num, i, j, change = 0, change2 = 0;
  char s[200000];
  char sb[200000];
  if (getNumsInt32((int32_t *)&num, (int32_t)1) == -1) {
    return -1;
  }
  if (scanf("%s", s) == EOF) {
    return -1;
  }
  strncpy(sb, s, num);
  for (i = 1; i < num; i++) {
    if (s[i - 1] == '#' && s[i] == '.') {
      s[i] = '#';
      change++;
    }
  }
  for (i = 1; i < num; i++) {
    if (sb[i - 1] == '#' && sb[i] == '.') {
      sb[i - 1] = '.';
      change2++;
      for (j = i - 2; j >= 0; j--) {
        if (sb[j] == '#') {
          sb[j] = '.';
          change2++;
        } else {
          break;
        }
      }
    }
  }
  if (change2 > 0) {
    if (change > change2) {
      change = change2;
    }
  }
  printf("%d\n", change);
  return 0;
}
