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