fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let mut n: Vec<char> = n.trim().chars().collect();

    n.reverse();
    (3..n.len()).step_by(3).rev().for_each(|i| n.insert(i, ','));
    n.reverse();

    let n: String = n.iter().collect();

    println!("{}", n);
}