#include <iostream>
#include <string>

using namespace std;

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

    int cnt = 0;
    char* ptr = &S[0];

    while (*(ptr + 3) && *(ptr + 1)) {
        if (*ptr == 'T' && *(ptr - 1) == 'C' && *(ptr - 2) == 'P' && *(ptr - 3) == 'C') {
            if (*(ptr + 1) == 'F') {
                cnt++;
                ptr += 5;
            } else if (*(ptr + 1) == 'C' && *(ptr + 2) == 'P' && *(ptr + 3) == 'C') {
                cnt++;
                ptr += 7;
            } else {
                ptr += 4;
            }
        } else {
            ptr++;
        }
    }

    cout << cnt << endl;

    return 0;
}