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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <string> 
#include <iomanip>
#include <cstdio>
#include <stdlib.h>
#include <string.h>
#include <vector>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <queue>
using namespace std;






int main()
{
	int N, K;
	cin >> N >> K;

	long long count = 0;


	for (int b = K+1; b <= N;b++) {
		count += N / b *max(b - K, 0);
		count += max(0, N % b  - K);
	}

	if (K == 0) {
		count -= N;
	}

	cout << count;
    return 0;
}