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

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using ll = long long int;
using vi = vector<int>;
using vvi = vector<vi>;

int main() {
  int N;
  cin >> N;
  string S;
  cin >> S;
  string s1 = "CPC";
  int i = 0;
  int n = 0;
  while (i < N - 4) {
    bool match = true;
    rep(j, 3) {
      if (S[i + j] != s1[j])
	match = false;
    }
    if (match) {
      if (S[i + 3] == 'T') {
	if (S[i + 4] == 'F') {
	  n++;
	  i += 3;
	} else {
	  bool submatch = true;
	  rep(j, 3) {
	    if (S[i + 4 + j] != s1[j])
	      submatch = false;
	  }
	  if (submatch) {
	    n++;
	    i += 6;
	  }
	}
      }
    }
    i++;
  }
  cout << n << endl;
  return 0;
}