import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val h = sc.nextLong()
    val w = sc.nextLong()

    println(pana2020b(h, w))
}

private fun pana2020b(h: Long, w: Long): Long {
  if (h == 1L || w == 1L ) return 1L

  val h1 = h / 2L
  val h2 = h - h1
  val w1 = w / 2L
  val w2 = w - w1

  var ans = h1 * w1 + h2 * w2

  return ans
}