$n=<>;$s=<>;$t=<>;
$x=$s=~y/2//;
$y=$t=~y/2//;
if($x|$y){
	print+($x+$y)*$n-$x*$y;
}else{
	$x=$s=~y/1//+0;
	$y=$s=~y/1//+0;
	print$x>$y?$x:$y;
}