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

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int N;
	string s;
	cin >> N >> s;
	int i = 0, ans = 0;
	while(1) {
		auto p = s.find("CPCT", i);
		if(p == string::npos) break;
		int j = p;
		if(s.substr(j + 4, 3) == "CPC") {
			ans++;
			i = j + 7;
		}
		else if(s.substr(j + 4, 1) == "F") {
			ans++;
			i = j + 5;
		}
		else i = j + 4;
	}
	cout << ans << endl;
}