Suppose that, in addition to edge capacities, a flow network has vertex capacities. That is each vertex v has a limit l(v) on how much flow can pass through v. Show how to transform a flow network G = (V, E) with vertex capacities into an equivalent flow network G = (V', E) without vertex capacities, such that a maximum flow in G' has the same value as a maximum flow in G. How many vertices and edges does G' have