Intervals: [[1,2], [2,3], [3,4], [1,3]]. Sorted by end: [[1,2], [2,3], [1,3], [3,4]]. Select [1,2]. Last end = .
[2,3]: start >= . Select! Last end = .
[1,3]: start < . Conflicts. Skip.
[3,4]: start >= . Select! Last end = . Max non-overlapping: . Total intervals: . Minimum removals: - = . The removed interval is [1,3]. Notice touching intervals like [2,3] and [3,4] are allowed. The overlap check is start >= lastEnd.