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