Problem:
Score : 400 points

Problem Statement

Takahashi had a pair of two positive integers not exceeding N, (a,b), which he has forgotten.
He remembers that the remainder of a divided by b was greater than or equal to K.
Find the number of possible pairs that he may have had.

Constraints

1 \leq N \leq 10^5

0 \leq K \leq N-1

All input values are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of possible pairs that he may have had.

Sample Input 1

5 2

Sample Output 1

7

There are seven possible pairs: (2,3),(5,3),(2,4),(3,4),(2,5),(3,5) and (4,5).

Sample Input 2

10 0

Sample Output 2

100

Sample Input 3

31415 9265

Sample Output 3

287927211

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

import java.util.Scanner

object Main {
  def solve(): Unit = {
    val sc = new Scanner(System.in)
    val N = sc.nextInt()
    val K = sc.nextInt()
    val sum = K match {
      case 0 => N * N
      case _ => ((K + 1 to N) map { b =>
        (N / b) * (b - K) + math.max(N % b - (K - 1), 0)
      }).sum
    }
    println(sum)
  }

  def main(args: Array[String]): Unit = {
    solve()
  }
}