#include <bits/stdc++.h>
int main(void) {
  int N, start, end, initial_black, initial_white, black, white;
  char *S;
  scanf("%d", &N);
  S = (char *)malloc(sizeof(char) * (N + 1));
  assert(S);
  for (start = 0, scanf("%s", S); start < N && S[start] == '.'; start++)
    ;
  for (end = N - 1; end >= 0 && S[end] == '#'; end--)
    ;
  if (end < start) {
    putchar('0');
    free(S);
    return 0;
  }
  for (initial_black = 0; S[start] == '#'; start++, initial_black++)
    ;
  for (initial_white = 0; S[start] == '.'; start++, initial_white++)
    ;
  for (black = 0, white = 0; start <= end; start++) {
    if (S[start] == '.') {
      white += 1;
    } else {
      black += 1;
    }
  }
  if (initial_black + white < initial_white + white &&
      initial_black + white < initial_black + black) {
    printf("%d", initial_black + white);
  } else if (initial_black + black < initial_white + white &&
             initial_black + black < initial_black + white) {
    printf("%d", initial_black + black);
  } else {
    printf("%d", initial_white + white);
  }
  free(S);
  return 0;
}
