import java.io.{BufferedOutputStream, BufferedReader, InputStreamReader, PrintWriter}

object Main {
  def main(args: Array[String]): Unit = {
    val in = new BufferedReader(new InputStreamReader(System.in))
    val out = new PrintWriter(new BufferedOutputStream(System.out))
    val Array(h, w) = in.readLine().split("\\s+").map(_.toLong)

    out.println(
      if (h == 1 || w == 1) {
        1
      } else {
        ((w + 1) / 2) * ((h + 1) / 2) + (w / 2) * (h / 2)
      }
    )
    out.flush()
  }
}
