Scanf.scanf "%d" (fun n ->
    let a = Array.init n (fun _ -> Scanf.scanf " %d" (fun a -> a)) in
    Array.sort compare a;
    let rec loop i acc =
        if i = n then acc else
            loop (i + 1) (acc + abs (i + 1 - a.(i)))
    in
    loop 0 0 |> Printf.printf "%d\n"
)