vr_map => sub { # https://www.perlmonks.org/?node_id=1229415
                my @list = @input;
                @list = unpack 'i*', pack 'I*', sort { $a <=> $b }
                        map { ~$_ } @list; # Doesn't even give the correct answer, there's an offset of 1
                Compare(\@list,\@output) or die "@list" if DO_CHECK;
              },