let rec f xs =
    try
        f (input_line stdin::xs)
    with End_of_file -> xs
    in
    let cmp x y =
        let xl = String.length x in
        let yl = String.length y in
        if xl=yl
            then String.compare x y
            else xl-yl
    in
        List.map (fun x->Printf.printf "%s\n" x) (List.sort cmp (f []))
;;