use Graph::Directed;

my @array1 = qw(dog cat rat mouse);
my @array2 = qw(dog rat mouse bird);
my @array3 = qw(cat rat fish mouse);

my $graph = Graph::Directed->new;

$graph->add_path(@array1);
$graph->add_path(@array2);
$graph->add_path(@array3);

my @toposort = $graph->toposort;

print "@toposort\n";

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dog cat rat fish mouse bird