#include <iostream>
#include <string>

using namespace std;

int main() {
    int N;
    cin >> N;
    string S;
    cin >> S;

    // "CPCTF" の数を数える
    int count_CPCTF = 0;
    for (int i = 0; i < N - 4; ++i) {
        if (S.substr(i, 5) == "CPCTF") {
            ++count_CPCTF;
            // "CPCTF" を "-" に置換
            S.replace(i, 5, "-----");
        }
    }

    // "CPCTCPC" の数を数え、先ほど数えた数に加算
    int count_CPCTCPC = 0;
    for (int i = 0; i < N - 6; ++i) {
        if (S.substr(i, 7) == "CPCTCPC") {
            ++count_CPCTCPC;
        }
    }

    cout << count_CPCTF + count_CPCTCPC << endl;

    return 0;
}