Refer to the partially solved minimum cost network flow problem of Exercise 10-25.

(a) Verify that the given flow is feasible.

(b) Construct the residual digraph corresponding to the current flow.

(c) Use Floyd-Warshall Algorithm 9B on your residual digraph to identify an improving feasible cycle direction with respect to the given flow.

(d) Compute the maximum feasible step l that could be applied to your cycle direction.