let array_of_string s = Array.init (String.length s) (fun i -> s.[i])

let () =
  read_line ()
  |> array_of_string
  |> Array.map (fun c -> Char.code c - Char.code '0')
  |> Array.to_list
  |> (fun (h :: t) -> List.fold_left (fun acc d ->
      List.concat @@ List.map (fun (x, s) ->
        [ (x + d, Printf.sprintf "%s+%d" s d);
          (x - d, Printf.sprintf "%s-%d" s d) ]) acc) [(h, string_of_int h)] t)
  |> List.find (fun (x, _) -> x = 7)
  |> snd
  |> Printf.printf "%s=7"