Problem:
Score : 400 points

Problem Statement

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 1

3 4
4 3
4 1
2 2

Sample Output 1

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.

Sample Input 2

5 3
1 2
1 3
1 4
2 1
2 3

Sample Output 2

10

Sample Input 3

1 1
2 1

Sample Output 3

0

Solution in Scala (2.11.7) (judge verdict: Wrong Answer)

import scala.collection.mutable.PriorityQueue

case class fuckingJob(days : Int , money : Int)

object Main extends App{
  val sc = new java.util.Scanner(System.in)
  val n = sc.nextInt() //job
  val m = sc.nextInt() //day
  var mwhile = m - 1
  val ab : PriorityQueue[fuckingJob] = PriorityQueue()(Ordering.by(_.money))
  var ans = 0

  for (i <- 0 until n) {
    val a = sc.nextInt()
    val b = sc.nextInt()
    ab.enqueue(fuckingJob(a,b))
  }

  while(mwhile >= 0 && ab.nonEmpty){
    val wara  = ab.dequeue()
    if(wara.days <= mwhile+1){
      ans += wara.money
      mwhile = mwhile - 1
    }
  
  }
  
  println(ans)
}