Scanf.scanf "%d" (fun n ->
    let q = Array.make 36 false in
    for i = 1 to n do
        Scanf.scanf " %d" (fun a -> q.(a) <- true)
    done;
    let rec loop i acc =
        if i = 36 then acc else
            loop (i + 1) (acc + if q.(i) && not q.(i - 1) then i else 0)
    in
    loop 1 0 |> Printf.printf "%d\n"
)