fn main() {
    let mut hw = String::new();
    std::io::stdin().read_line(&mut hw).ok();
    let hw: Vec<usize> = hw.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let h = hw[0];
    let w = hw[1];
    let mut result: Vec<usize> = vec![];
    for _ in 0..h {
        let mut a = String::new();
        std::io::stdin().read_line(&mut a).ok();
        a.trim().split_whitespace().map(|s| s.parse::<usize>().unwrap()).for_each(|i| result.push(i));
    }
    result.sort();
    for j in 0..h {
        println!("{}", result.iter().skip(j*w).take(w).map(|i| i.to_string()).collect::<Vec<String>>().join(" "));
    }
}