Recipe Clusters

**Problem.** Line 1: n m. Then m lines: u v (a directed dependency u depends on v). Print the size of the largest set of items that are mutually reachable (directly or transitively). **Constraints:** 1 <= n <= 50000; 0 <= m <= 120000. **R versus W.** The graded wrong solution labels components by forward reach from each unvisited node — a cycle plus everything it can reach becomes one fake cluster. Target: full solve within 40 minutes.