#include <iostream>
#include <vector>
#include <set>
#include <string>
#include <algorithm>

using namespace std;


int main() {
    int n; string s;
    cin >> n >> s;

    int count = 0;

    for (int i = s.size() - 1; i >= 6; i--) {
        //cout << "Yo";
        if(s.substr(i - 6, 7) == "CPCTCPC"){
            s.replace(i - 6, 7, "CPCTF");
            i -= 3;
            //cout << s << endl;
        }
    }

    for (int i = s.size() - 1; i >= 4; i--) {
        //cout << "Yo";
        if(s.substr(i - 4, 5) == "CPCTF"){
            i -= 4;
            count++;
            //cout << s << i << endl;
        }
    }

    cout << count;
    return 0;
}