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