题目描述
There are N one-off jobs available. If you take the i-th job and complete it, you will earn the reward of B_i after A_i days from the day you do it.
You can take and complete at most one of these jobs in a day.
However, you cannot retake a job that you have already done.
Find the maximum total reward that you can earn no later than M days from today.
You can already start working today.
-----Constraints-----
- All values in input are integers.
- $1 \leq N \leq 10^5$
- $1 \leq M \leq 10^5$
- $1 \leq A_i \leq 10^5$
- $1 \leq B_i \leq 10^4$
-----Input-----
Input is given from Standard Input in the following format:
N M
A_1 B_1
A_2 B_2
$\vdots$
A_N B_N
-----Output-----
Print the maximum total reward that you can earn no later than M days from today.
-----Sample Input-----
3 4
4 3
4 1
2 2
-----Sample Output-----
5
You can earn the total reward of 5 by taking the jobs as follows:
- Take and complete the first job today. You will earn the reward of 3 after four days from today.
- Take and complete the third job tomorrow. You will earn the reward of 2 after two days from tomorrow, that is, after three days from today.
输入格式
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输出格式
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