#!/usr/bin/perl -w
use strict;

use Graph::Undirected;

my $graph = Graph::Undirected->new();

my @data = map { [ grep defined, split /\s+/ ] } <DATA>;

foreach my $line ( 1 .. scalar @data ) {
  $graph->add_edges( map { $line => $_ } @{ $data[ $line - 1 ] } )
} 

my @sets = $graph->strongly_connected_components;

for (@sets) {
  printf "{ %s }\n", join ' ', sort { $a cmp $b } @$_;
}

__END__
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