$listA[0] = [qw(1 foo bar)];
$listB[0] = [qw(1 bar baz)];

print "First record from \@listA: $listA[0][0]\n";

@listToExpire = grep { } @listB;

##</code><code>##

my @listToExpire = grep { my $a = $_; (grep /$a/, @listA) ? () : ($a); } @listB;