DIY: Find Interval Sets

Problem statement

You are given a list of intervals, and you have to organize them into sets such that only one interval can occupy a set at a time. Your job is to find the minimum number of sets we need to process all the intervals.

Input

The input is a list of lists. The nested lists contain two integers representing the starting and ending points of the interval. The following is an example of input:

[[1, 4], [2, 5], [4, 8], [5, 6], [5, 8], [6, 7]]

Output

The output is an integer representing the number of sets needed to process the intervals. The following is an example output:

3

Coding exercise

You need to implement the function find_sets(intervals), where intervals is the list of intervals. The function returns an integer representing the number of sets that are needed.