object Main extends App{
  val Array(h,w) = scala.io.StdIn.readLine.split(" ").map(_.toInt)
  val a = BigInt((h/2.0).ceil.toInt)
  val b = BigInt((w/2.0).ceil.toInt)
  val c = BigInt((h/2.0).floor.toInt)
  val d = BigInt((w/2.0).floor.toInt)

  println((a*b+c*d).toInt)
}