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