#include <bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin >> n;
	string a;
	cin >> a;
	string str1 = regex_replace(a, regex("CPCTCPC"), "CPCTF");
	int count = 0;
	for(int i=0;i<str1.size()-4;i++){
		if(str1.substr(i,5) == "CPCTF"){
			count++;
		}
	}
	cout << count << endl;
}