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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;

public class Main {

  public static void main(String args[])
  {
    	Scanner sc = new Scanner(System.in);
    	String input = sc.nextLine();
    	String[] inputs = input.split(" ");
    	long n = Long.valueOf(inputs[0]);
    	long k  = Long.valueOf(inputs[1]);
    	long sum = 0;
  		for( long div = k+1; div<=n;div++)  {
		
            long a =n/div;
          	long count = a*(div-k);
          	long r = n%div;
          	if(r>=k)
            {
              count  = count + r- k+1;
            }
          sum +=count;
        }
    	System.out.println(sum);
  }
}