Let G = (V, E) be a directed graph. Two directed paths in G are called edge-disjoint if they have no common edges (they may have common vertices). Suppose that two vertices s, t are given in G.

(a) Show an efficient algorithm to decide whether there are two edge-disjoint directed paths from s to t.

(b) Show that if there is no such pair of paths then either there is no directed path from s to t, or there is an edge with the property that every directed from s to t passes through it.