let string_to_bytes s =
  let b = Bytes.create (String.length s) in
  Bytes.iteri (fun i c -> Bytes.set b i s.[i]) b;
  b

let solve s =
  let b = string_to_bytes s in
  Bytes.set b 3 '8';
  Bytes.to_string b

let _ = read_line () |> solve |> print_endline