Module Module1

    Sub Main()

        Dim tmp As String() = Split(Console.ReadLine(), " ")
        Dim H As Integer = CInt(tmp(0))
        Dim W As Integer = CInt(tmp(1))

        Dim wkH As Integer = 0
        If H Mod 2 <> 0 Then
            wkH = 1
        End If
        Dim wkW As Integer = 0
        If W Mod 2 <> 0 Then
            wkw = 1
        End If

        Dim wk As Long = CLng((H + wkH)) * CLng((W + wkW)) \ 2
        Dim tate = (Int((W + 1) / 2) * wkH)
        If wkW = 1 AndAlso tate > 0 Then
            tate -= 1
        End If

        Dim yoko = (Int((H + 1) / 2) * wkw)
        If wkH = 1 AndAlso yoko > 0 Then
            yoko -= 1
        End If
        wk = wk - (tate * wkH) - (yoko * wkW) - (wkH * wkW)

        Console.WriteLine(wk)

    End Sub

End Module
