let c0 = int_of_char '0'
let c9 = int_of_char '9'

let solve str =
  let lstr = String.length str in
  let rec solve' idx result =
    if idx >= lstr then result
    else
      let c = int_of_char str.[idx] in
      let nextResult =
        if c0 <= c && c <= c9 then result + c - c0
        else result
      in
      solve' (idx + 1) nextResult
  in
  solve' 0 0

let () =
  let s = read_line () in
  solve s |> string_of_int |> print_endline