print "Number: ", scalar @subgraphs, "\n";
print "First: ", @{ $subgraphs[0] }, "\n";

##</code><code>##

my @subg;
for my $component (0 .. @subgraphs - 1) {
    $subg[$component] = Graph::Undirected->new;
    for my $i (0 .. $#a) {
        $subg[$component]->add_edge($a[$i], $b[$i])
            if grep $_ eq $a[$i], @{ $subgraphs[$component] };
    }
}