Suppose that, in addition to edge capacities, a flow network has vertex capacities. That is each vertex has a limit l() on how much

Suppose that, in addition to edge capacities, a flow network has vertex capacities. That is each vertex ν has a limit l(ν) on how much flow can pass through ν. 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?