Exercise 3 (Topologically Sorting a DAG) Consider the following directed acyclic graph. Per form a depth-first search by hand, computing the pre and post times for each vertex; whenever theres a choice of verrtices, pick the one with the lower number. Use the post numbers to generate a topological sort of the vertices. That is, assign a number to each vertex such that for every edge (u, v), u has a lower number than v. 6 3