You are given a set of n unit-length tasks, i.e., each task has length 1. Each task i, for 1 i n, can start at the earliest possible time r_i and must finish by its deadline d_i. You are asked to schedule a maximum number of tasks within the given constraint, so that all the picked tasks can be scheduled without conflicts. Describe your strategy on picking what tasks and how to schedule them. Explain why your strategy works.