use strict;
use warnings;

my @list = qw(AGCT AGGT GG AGCT);

my %bucket;
for (@list) {
	push @{$bucket{length($_)}}, $_;
}

# Only want to sort these once.
my @sizes = sort {$a <=> $b} keys %bucket;

while (my $size = shift @sizes) {
	MAIN: for my $i (0..$#{$bucket{$size}}) {
		# Same Size first
		for my $j ($i+1..$#{$bucket{$size}}) {
			if ($bucket{$size}[$i] eq $bucket{$size}[$j]) {
				undef $bucket{$size}[$i];
				next MAIN;
			}
		}
		
		# Bigger strings
		my $substr_re = qr/$bucket{$size}[$i]/;
		for my $bigger (@sizes) {
			for my $str (@{$bucket{$bigger}}) {
				if ($str =~ $substr_re) {
					undef $bucket{$size}[$i];
					next MAIN;
				}
			}
		}
	}
}

my @unique = grep {defined} map {@$_} values %bucket;

print "$_\n" for @unique;