272. Course Schedule III

There are `n` different online courses numbered from `1` to `n`. You are given an array `courses` where `courses[i] = [duration_i, lastDay_i]` indicate that the `i`th course should be taken **continuously** for `duration_i` days and must be finished before or on `lastDay_i`. You will start on the `1st` day and you cannot take two or more courses simultaneously. Return the **maximum number of courses** that you can take.