#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int out = 0;
  int count = 0;
  for (int i = 0; i < s.size(); i++) {
    if (i == 0) {
      for (int j = 0; j < s.size(); j++) {
        if (s.at(j) == '.') count++;
        out = count;
      }
    } else {
      if (s.at(i - 1) == '.' & s.at(i) == '.') {
        count--;
      } else if (s.at(i - 1) == '#' & s.at(i) == '#') {
        count++;
      } else if (s.at(i - 1) == '.' & s.at(i) == '#') {
        count--;
      } else if (s.at(i - 1) == '#' & s.at(i) == '.') {
        count++;
      }
      if (out > count) {
        out = count;
      }
    }
  }
  cout << out;
}
