#include <iostream>
#include <string>
using namespace std;
int main() {
  int n; cin >> n;
  string s; cin >> s;
  int count = 0;
  for (int i = 0; i < n; i++){
    if (s.substr(i, 5) == "CPCTF"){
      count++;
    }else if (s.substr(i, 7) == "CPCTCPC"){
      count++;
    }
  }
  cout << count << endl;
  return 0;
}