Time Scheduler

You're working on a scheduler app. The user would like to attend as many events as possible but cannot attend events that overlap. Can you find the schedule with the greatest number of non-overlapping events?

See if you can find an O(n log n) solution.

I/O Format

You will be given a list of n numbers. The numbers consist of n/2 pairs, where each pair is the start and end time of an event. Find the optimal schedule of events and print each time like this: [start , end].

Sample Input

1
8
4 8 1 3 7 9 5 6

Sample Output

[1,3] [5,6] [7,9]

Explanation
You are given 4 events:

[4,8] [1,3] [7,9] [5,6]

[4,8] overlaps with 2 other events, so it should be left out, but the other 3 can all be included.