Scanf.scanf "%d" (fun n ->
    let rec loop cur i mx =
        if cur = 1 then Printf.printf "%d\n%d\n" i mx else
            if cur mod 2 = 0 then loop (cur / 2) (i + 1) mx else
                loop (cur * 3 + 1) (i + 1) (max mx (cur * 3 + 1))
    in
    loop n 0 n
)