#include <bits/stdc++.h>
using namespace std;
int main() {
  long N, c0 = 0, c1 = 0;
  long count1;
  long sum = 0, min = LONG_MAX;
  string str;
  cin >> N >> str;
  for (int i = 0; i < N; i++) {
    if (str[i] == '.') {
      count1++;
    }
  }
  sum = count1;
  for (int i = 0; i < N; i++) {
    if (str[i] == '#') {
      sum++;
    } else {
      sum--;
    }
    if (sum < min) {
      min = sum;
    }
  }
  cout << min;
  return 0;
};
