public String toString()
	{
		String s = new String();
		s += V() + " vertices " + E() + " edges\n";
		for (int v = 0; v < V(); v++)
		{
			s += v + ": ";
			for (WeightedDirectedEdge e : adj[v])
				s += e + ", ";
			s += "\n";
		}
		return s;
	}