use strict;
use Data::Dumper;
my @in = (
        [qw[M N]],
        [qw[M N Q P O]],
        ['MN', 'QPO'],
        [qw[C B A]],
        ['C ', 'A', 'A],
        [qw[U S]],
        [qw[V T]],
        [qw[C G F E D]],
        [qw[C G F H]],
        [qw[C G F H I]],
        [qw[C G F H J]],
        [qw[M K]],
);

sub arrayrefs {
   my $lindex = $#$a < $#$b ? $#$a : $#$b;
   for (0 .. $lindex) {
        return $$a[$_] cmp $$b[$_] unless $$a[$_] eq $$b[$_];
   }
   #equal or less
   return $#$a <=> $#$b;
}

my @out = sort arrayrefs @in;
print Dumper @out;