let () =
  let rec divisor n m lst =
    if n < m * m then lst
    else if n mod m = 0 then
      if m = n / m then divisor n (m+1) (m :: lst)
      else divisor n (m+1) (m :: (n / m) :: lst)
    else divisor n (m+1) lst in
  Scanf.scanf "%d\n" @@ fun n ->
  let ans = List.fold_left (+) 0 (divisor n 1 []) in
  Printf.printf "%d\n" ans