#include <bits/stdc++.h>
using namespace std;
#define int long long

signed main() {
  int n;
  string s;
  cin >> n >> s;
  int i = n - 1;
  int ans = 0;
  while (i >= 0) {
    string sl = s.substr(i, 7), ss = s.substr(i, 5);
    if (ss == "CPCTF" || sl == "CPCTCPC") {
      ans++;
    }
    i--;
  }
  cout << ans << endl;
}