Maximum Total Deadline Margin

You are given an array tasks, where tasks[i] = [duration, deadline].

You process every task one at a time, in an order you choose, starting at time 0 with no gaps: a task started at time t finishes at time t + duration.

Each task scores deadline - finishTime, positive when it finishes early and negative when it finishes late.

Return the maximum possible total score over all processing orders.

Examples

Example 1

Input: tasks = [[6,10],[8,15],[5,12]]
Output: 2
Explanation: Process in ascending duration order (5, 6, 8). Finish times are 5, 11 and 19, scoring (12 - 5) + (10 - 11) + (15 - 19) = 7 - 1 - 4 = 2. No order does better.

Example 2

Input: tasks = [[4,2]]
Output: -2
Explanation: The only task finishes at time 4 against deadline 2, so the total is negative.