You are given a rooted tree. Answer queries of this form: how many nodes are at depth exactly d and have their LCA with node v at depth exactly h?
In other words, count v's "cousins" at a specific depth and distance. You are filtering by both depth and ancestor level. There are up to , nodes and , queries. You need efficient filtering.
The approach: lift v to depth h using binary lifting. Then count descendants of that ancestor at depth d. Euler tour flattening helps make the counting efficient.