<>;
@d=sort{$b-$a}glob<>;
($x,$y)=glob<>;

if($x==0&&$y==0){
	print 0;
	exit;
}

$z=abs($x)+abs($y);
if(grep$z==$_,@d){
	print 1;
	exit;
}

($e[0])=grep{$_%2==0}@d;
($e[1])=grep{$_%2==1}@d;

if(grep{$zd=abs($z-$_);$e[$zd&1]>=$zd}@d){
	print 2;
	exit;
}

print -1;