Clinic: The Interval Illusion

**Bài toán.** Choose the maximum number of pairwise non-overlapping intervals. Overlap at a shared endpoint is allowed only if one ends exactly where the other starts? NO — shared endpoints count as overlap here: [1,3] and [3,5] DO overlap. n ≤ 200000. **The submission below sorts by start and takes greedily — Wrong Answer.** Produce the counterexample, name the class, fix it. ``cpp sort by start; take interval if start >= lastEnd; ``