use proconio::input;

const HAPPY: &str = "HAPPY";

fn main() {
    input! {
        n: usize,
        s: String,
    }

    let (head, tail) = s.split_at(n - HAPPY.len());

    let mut head_cost = 0;
    for i in 0..head.len() {
        if i + HAPPY.len() > head.len() {
            break;
        }

        head_cost += (&head[i..i + HAPPY.len()] == HAPPY) as usize;
    }

    let tail_cost = tail
        .chars()
        .zip(HAPPY.chars())
        .filter(|&(ch1, ch2)| ch1 != ch2)
        .count();

    println!("{}", head_cost + tail_cost);
}