#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int i, cnt = 0;
  for (i = 0; i < s.size(); i++) {
    if (s[i] == 'x' && s[i + 1] == 'x' && s[i + 2] == 'x' && i < n - 2) cnt++;
  }
  cout << cnt << endl;
}
