#!/usr/bin/perl -wT
use strict;

# one ordering....
my $letters = ',A,C,G,N,T';
my @list1 = grep {/./} glob("{$letters}"x4);
print "L1: $_\n" for @list1;

# different ordering
my $letter2 = 'A,C,G,N,T';
my @list2 = (glob("{$letter2}"x2),glob("{$letter2}"x3),glob("{$letter2}"x4));
print "L2: $_\n" for @list2;