fn main() {
    let mut abcd = String::new();
    std::io::stdin().read_line(&mut abcd).ok();
    let mut abcd: Vec<isize> = abcd.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    abcd.sort();
    if (0..2).rev().map(|i| abcd[i+1] - abcd[i]).any(|i| i != 1) {
        println!("No");
    } else {
        println!("Yes");
    }
}