#![allow(non_snake_case)]
use proconio::{input, marker::Bytes};

fn main() {
    input! { n: usize, s: Bytes }
    let mut ans = 0;
    let mut i = 0;
    while i < n {
        if i + 5 <= n && s[i..i+5] == [67, 80, 67, 84, 70] {
            ans += 1;
            i += 5;
        } else if i + 7 <= n && s[i..i+7] == [67, 80, 67, 84, 67, 80, 67] {
            ans += 1;
            i += 7;
        } else {
            i += 1;
        }
    }
    println!("{ans}");
}