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

let () = Scanf.sscanf (read_line ()) "%f %f" (
        fun h w -> 
                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"
