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