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

int main() {
  int N;
  string S;
  cin >> N >> S;
  int count = 0;
  
  for (int i = 0; i < N; i++){
    if (S.substr(i, 5) == "CPCTF"){
     count++;
    }
    
    if (S.substr(i, 7) == "CPCTCPC"){
     count++;
     i += 6;
    }
  }
  
  cout << count << endl;
}