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