#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  cin >> n >> s;
  int cnt = 0;
  for (int i = 0; i < n - 2; i++) {
    if (s.substr(i, 3) == "xxx") cnt++;
  }
  cout << cnt << endl;
}
