https://www.luogu.org/problem/P3469
Translation: a no connectivity to the original map, you can delete a point in the figure, and quantity ordered points to delete this point because as a result of not communicating right. Or, after deleting this point, the product of the size of each connected component and?
Of course, considering Tarjan AFP learned find cut points. Tarjan again point to each record that he is not cut point. Then, when the second pass for each cut point, its statistical respective divided sub-tree (and the father, if any) the contribution of communication between these blocks.