The problem essentially goes:

You have people who live and die at certain years. In what year are the maximum amount of people alive?

To do this, make an array of pairs. The first pair has the year, and the second pair is a boolean, determing whether it is a death year or a birth year. Sort all years, create a variable which stores the maximum, and if you encounter a new max, store that current year. Then print out your year and your maximum.