object Main extends App{
    val Array(h,w) = scala.io.StdIn.readLine.split(" ").map(_.toInt)
    val output = BigDecimal((h/2.0).ceil)  * (w/2.0).ceil + (h/2.0).floor * (w/2.0).floor
    println(output.toString.take(output.toString.indexOf('.')))
}
