Module b

ABC 394 B - cat

refs: https://atcoder.jp/contests/abc394/tasks/abc394_b

use proconio::input;

fn main() {
    input! {
        n: usize,
        mut s: [String; n],
    }

    s.sort_by_key(|t| t.len());
    println!("{}", s.join(""));
}