public Digraph digraph()
	{
		Digraph g = new Digraph(V());

		try
		{
			for (WeightedDirectedEdge e : edges())
				g.addEdge(e.from(), e.to());
		}
		catch (Exception e)
		{
			e.printStackTrace();
			System.exit(1);
		}
		return g;
	}