OCaml

let main () =
  let gr () = Scanf.scanf " %f" (fun i -> i) in 
  let n = gr () in
  let m = gr () in
  let a = gr () in
  let f x y = ceil (x /. y) in
  Printf.printf "%.0f\n" ((f n a) *. (f m a))
  ;;
let _ = main();;

Scala

object Main extends App {
 val Array(n, m, a) = readLine.split(" ").map(_.toLong)
 def roundUp(x: Long) = x / a + (if (x % a > 0) 1 else 0)
 println(roundUp(n) * roundUp(m))
}