#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const long long LINF = 1e18;
const int MOD = 1e9 + 7;
int main() {
  int n;
  string s;
  cin >> n >> s;
  int ans = 0;
  for (int i = n - 2; i >= 0; i--) {
    if (s[i] == '#' && s[i + 1] == '.') ans++;
  }
  cout << ans << endl;
}
