fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

fn main() {
    let v = read_vec::<usize>();
    let (a, b) = (v[0], v[1]);
    let mut ans = 3;
    for num in a..b + 1 {
        if num >= 23 && num <= 25 {
            ans -= 1;
        }
    }
    println!("{}", ans);
}