let () =
  Scanf.scanf "%d %d %d" (fun a b c ->
    let m = max a (max b c) in
    let a, b, c = m-a, m-b, m-c in
    a/2 + b/2 + c/2 + [|0;2;1|].(a mod 2 + b mod 2 + c mod 2))
  |> Printf.printf "%d\n"