Remove Covered - Implementation

function removeCoveredIntervals(intervals)
 sort intervals by (start ascending, end descending)
 count := 0
 maxEnd := 0
 for each interval in intervals
 if interval.end > maxEnd then
 count := count + 1
 maxEnd := interval.end
 return count

Time: $O(n \log n)$. Space: $O(1)$ extra.