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

int main()
{
    int N;
    string S;
    cin >> N >> S;
    int ans = 0;
    for (int i = 0; i < N - 3;)
    {
        if (S.substr(i, 4) == "CPCT")
        {
            if (S[i + 4] == 'F')
            {
                ans++;
                i += 5;
                continue;
            }
            if (S.substr(i + 4, 3) == "CPC")
            {
                ans++;
                i += 7;
                continue;
            }
        }
        i++;
    }
    cout << ans;
}

// CPCTF
// CPCTCPC
// CPCTCPCTCPC
// CPCTFCPCTF