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

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1ll << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD (ll)1000000007
#define P pair<ll, ll>

int main(){
    int n, ans = 0;
    string s;
    cin >> n >> s;
    REP(i, n){
        if(i + 5 <= n and s.substr(i, 5) == "CPCTF"){
            ans++;
            i += 4;
        }
        else if(i + 7 <= n and s.substr(i, 7) == "CPCTCPC"){
            ans++;
            i += 6;
        }
    }
    cout << ans << endl;
}