Suppose that you are given a flow network G, and G has edges entering the source s. Let f be a flow in G in which one of the edges (ν, s) entering the source has f (ν, s) = 1. Prove that there must exist another flow f′ with f′(ν, s) = 0 such that |f| = |f′|. Give an O(E)-time algorithm to compute f′, given f, and assuming that all edge capacities are integers.