use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let mut s: Vec<char> = itr.next().unwrap().chars().collect();
    s.reverse();
    let mut t: Vec<char> = Vec::new();
    for i in 0..s.len() {
        if i != 0 && i % 3 == 0 {
            t.push(',');
        }
        t.push(s[i]);
    }
    let t: String = t.into_iter().rev().collect();
    println!("{}", t);
}