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