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

int main(){
    int n;cin >> n;
    string s;cin >> s;
    int k=0,x=0;
    while(k+4<n){
        if(k+4<n){
            if(s[k]=='C' && s[k+1]=='P' && s[k+2]=='C' && s[k+3]=='T'){
                if(s[k+4]=='F'){
                    k+=5;
                    x++;
                }else if(k+6<n && s[k+4]=='C' && s[k+5]=='P' && s[k+6]=='C'){
                    k+=7;
                    x++;
                }else{
                    k+=4;
                }
            }else{
                k++;
            }
        }
    }
    cout << x << "\n";
}