- Time limit: 1.00 s
- Memory limit: 512 MB
You have to process n tasks. Each task has a duration and a deadline, and you will process the tasks in some order one after another. Your reward for a task is d-f where d is its deadline and f is your finishing time. (The starting time is 0, and you have to process all tasks even if a task would yield negative reward.)
What is your maximum reward if you act optimally?
Input
The first input line has an integer n: the number of tasks.
After this, there are n lines that describe the tasks. Each line has two integers a and d: the duration and deadline of the task.
Output
Print one integer: the maximum reward.
Constraints
- 1 \le n \le 2 \cdot 10^5
- 1 \le a,d \le 10^6
Example
Input:
3 6 10 8 15 5 12
Output:
2