use strict;

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

my @result = ();
while (@data) {
	push @result, $data[0];
	@data = grep { $data[0] !~ /\Q$_\E/  } @data;
}

print "@result\n";

##</code><code>##

...
while (@data) {
	push @result, $data[0];
	@data = grep { index($data[0], $_) == -1 } @data;
}
...