#include <bits/stdc++.h>
#define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define reps(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
#define rrep(i, n) for(int i=((int)(n)-1); i>=0; --i)
#define rreps(i, n) for(int i=((int)(n)); i>0; --i)
#define all(v) (v).begin(), (v).end()
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vvvi = vector<vector<vector<int>>>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;
using vs = vector<string>;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<class T>bool chmaxeq(T &a, const T &b) { if (a<=b) { a=b; return 1; } return 0; }
template<class T>bool chmineq(T &a, const T &b) { if (b<=a) { a=b; return 1; } return 0; }
bool yes(bool a) { cout << (a?"yes":"no") << endl; return a; }
bool Yes(bool a) { cout << (a?"Yes":"No") << endl; return a; }
bool YES(bool a) { cout << (a?"YES":"NO") << endl; return a; }
void _main();
int main() { cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(16); _main(); return 0; }

void _main() {
	int N; cin >> N;
	string S; cin >> S;
	int ans = 0;
	int pos = 0;
	while (pos < N) {
		if (pos+5<=N && S.substr(pos, 5)=="CPCTF") {
			ans++;
			pos += 5;
		}
		else if (pos+7<=N && S.substr(pos, 7)=="CPCTCPC") {
			ans++;
			pos += 7;
		}
	}
	cout << ans << endl;
}