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