use std::io::Read;

fn solve(a: usize, b: usize) {
    let count = (a..=b).filter(|i| vec![23, 24, 25].contains(i)).count();
    println!("{}", 3 - count);
}

fn main() {
    let mut ab = String::new();
    std::io::stdin().read_to_string(&mut ab).ok();
    let ab: Vec<usize> = ab.trim().split('\n').next().unwrap().trim().split_whitespace().map(|i| i.parse::<usize>().unwrap()).collect();
    solve(ab[0], ab[1]);
}