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.*;
import java.lang.*;
import java.io.*;

public class Main {
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        
        int n = scan.nextInt();
        int k = scan.nextInt();
        
        System.out.println(reminder(n,0,k,k+1));
    }
    
    private static long reminder(int n, long val, int k, int cur){
        if(cur > n) return val;
        if(k == 0) return n*n;
        
        while(cur <= n){
            int volume = cur - k;
            int cycle = n/cur;
            val += cycle * volume;
        
            int rest = n % cur;
            val += rest - k >= 0 ? rest - k + 1 : 0;
            
            cur++;
        }
        
        return val;
    }
}