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.*;
class Main {
   public static void main(String[] args)
   {
      Scanner scan = new Scanner(System.in);
      int     N    = scan.nextInt();
      int     K    = scan.nextInt();
      long    coun = 0;

      if(K == 0){
         coun = N * N;
         System.out.println(coun);
         return;
         }
      for(int i = 1; i <= N; i++){
          if(i > K){
             coun += (N / i) * (i - K) >= 0 ? (N / i) * (i - K) : 0;

             coun += (N % i) - K + 1 >= 0 ? (N % i) - K + 1 : 0;
             }
          }
      System.out.println(coun);
   }
}