sub max{$_[$_[1]>$_[0]]}
sub min{$_[$_[1]<$_[0]]}
sub odd{$_[$_[1]%2]}
sub equal{$_[0]==$_[1]}
$\=$/;

($W,$H)=glob<>;
if($W%2==0 && $H%2==0){
	print(($W+1)*($H+1)-max($W,$H)-equal($W,$H))
}elsif($W%2==1 && $H%2==1){
	print(($W+1)*($H+1)-min($W,$H))
}else{
	print(($W+1)*($H+1)-odd($W,$H))
}