use strict;
use Bit::Vector;

my @data = qw/a mnk ab m b bc abcd cd bcd bd m nk/;
@data = sort {length($b) <=> length($a)} @data;

@data = map [$_, uc($_), Bit::Vector->new_Enum(256, join(',', map ord($_), (split //, uc($_))))->Block_Read()], @data;

my @result = ();
while (@data) {
    push @result, $data[0][0];
	@data = grep { ($data[0][2] & $_->[2]) ne $_->[2] or index($data[0][1], $_->[1]) == -1 } @data;
}

print "@result\n";