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,K;
		N = sc.nextInt();
		K = sc.nextInt();
		long count =0;
		if (K==0) {
			System.out.println(N);
			return ;
		} else if (K==1){
			System.out.println(N-1);
			return ;
		}
		for (int i=K+1;i<=N;i++) {
			count +=(N/i)*(i-K) ;
			int c = N - (N / i ) * i;
			if (c >= K) {
				count = count+c-K+1;
			}
		}
		System.out.println(count);
	}
}