(*
ocamlfind ocamlopt -package batteries -linkpkg main.ml -o a.out
*)
open Batteries

let () = Scanf.sscanf (read_line ()) "%f %f" (
        fun h w -> 
                if h = 1.0 || w = 1.0 then
                        1
                else
                        let hb = floor (h /. 2.0) in
                        let hl = h -. hb in
                        let wb = floor (w /. 2.0) in
                        let wl = w -. wb in
                                int_of_float (hb *. wb +. hl *. wl)
) |> Printf.printf "%d\n"
