module S = Set.Make (struct
  type t = int
  let compare = (-)
end)

let () =
  let w, h, n = Scanf.scanf "%d %d %d " (fun w h n -> w, h, n) in
  let rec read i ss ks =
    if i = n then S.cardinal ss, S.cardinal ks
    else
      let s, k = Scanf.scanf "%d %d " (fun s k -> s, k) in
      let s, k = s - 1, k - 1 in
      read (i + 1) (S.add s ss) (S.add k ks) in
  let ns, nk = read 0 S.empty S.empty in
  ns * h + w * nk - ns * nk - n |> Printf.printf "%d\n"