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: Time Limit Exceeded)

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();
		int ans =0;
		for(int b =K+1;b<=N;b++){
		//	System.out.println("b実行" +b);
			for(int Q =0;b*Q <= N ;Q++){
				////System.out.println("Q実行"+Q);
				for(int R =K;R<b;R++){
					int a = b*Q+R;
					if(a<=N&&a>0){
						ans++;
					//	System.out.println("R実行"+R);
						//System.out.println(b*Q+R+""+b+""+Q+""+R);
					}
				}
			}
		}
		System.out.println(ans);
		sc.close();
	}
}