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