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

using ll = long long;
using llu = long long unsigned;

// メイン関数
int main() {
    int n;
    string s;
    cin >> n >> s;

    string t1 = "CPC";
    string t2 = "CPCTF";
    string t3 = "CPCTCPC";
    int ret = 0;
    for (int i=0; i<=n-5; ++i) {
        if (t2 == s.substr(i, t2.size())) {
            ret++;
            i+=t2.size();
        }
        if (t3 == s.substr(i, t3.size())) {
            ret++;
            i+=t3.size();
        }
    }
    cout << ret << endl; return 0;
}