use Graph;

my @AoA = (
	[11,29, 10,25],
	[15,35, 11,29],
	[15,15, 11,21],
	[10,25, 11,21],
	[15,35, 21,39],
	[25,40, 21,39],
	[21,11, 25,10],
	[15,15, 21,11],
	[35,35, 29,39],
	[29,39, 25,40],
	[35,15, 29,11],
	[25,10, 29,11],
	[40,25, 39,29],
	[35,35, 39,29],
	[39,21, 40,25],
	[35,15, 39,21],
);

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

for my $pair (@AoA)
{
	my ($x1, $y1, $x2, $y2) = @$pair;
	$graph->add_edge("$x1,$y1", "$x2,$y2");
}

print "$_\n" for $graph->find_a_cycle;