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.Scanner;

public class Main {
	public static void main (String[] args)  {
		Scanner sc = new Scanner(System.in);
	    int N = sc.nextInt(); int K = sc.nextInt(); long sum = 0;      
	      
	    if (K == 0){System.out.println(N*N); System.exit(0);}	      
	    for (int i=1; i<=N; i++) // b
	    	sum += (N/i) * Math.max(0, i-K)  + Math.max(0, (N%i)-K+1);
	    System.out.println(sum); sc.close();
    }
}