#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++;
  }
  if (cnt > 0)
    cout << cnt;
  else
    cout << 0;
  cout << '\n';
  return 0;
}
