#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
int t;
void solve() {
  int n, res = 0, j = 0;
  string s;
  cin >> n >> s;
  map<int, int> m;
  for (int i = 0; i <= n; i++) {
    if (s[i] == 'x') {
      m[j]++;
    } else {
      j++;
    }
  }
  for (auto i : m) {
    res += max(0, i.second - 2);
  }
  cout << res;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  if (0) {
    cin >> t;
    while (t--) solve();
  } else {
    solve();
  }
}
