use itertools::Itertools;
use proconio::{input, marker::Chars};

fn main() {
    input! {
        n: usize,
        mut s: Chars,
    }
    let happy = "HAPPY".chars().collect_vec();
    let mut ans = 0;
    for i in 0..5 {
        if s[n - 5 + i] != happy[i] {
            ans += 1;
        }
    }
    s.truncate(n - 5);
    while let Some(suffix) = s.last_chunk_mut::<5>() {
        if &suffix[..] == &happy {
            suffix[0] = '.';
            ans += 1;
        }
        s.pop();
    }
    println!("{ans}");
}