let to_list str =
  let rec doit i acc =
    if i < 0 then acc
    else doit (i - 1) (String.get str i :: acc) in
  doit (String.length str - 1) []

let () =
  read_line ()
  |> String.map (fun c -> if c >= '0' && c <= '9' then c else '0')
  |> to_list |> List.map (fun c -> Char.code c - Char.code '0')
  |> List.fold_left (+) 0 |> Printf.printf "%d\n"