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: Time Limit Exceeded)

#include<stdio.h>
#include<string.h>
#include<algorithm>
#define ll long long
//#include<iostream>
//using namespace std;
/*int cmp(int a,int b)
{
	return a>b;
 } */
int main()
{
	int n,k,kase=0,z;
	scanf("%d %d",&n,&k);
	if(k==0)  z=1;
	else z=k;
	for(int i=z;i<=n;i++)
	{
		for(int j=z;j<=n;j++)
		{
			if(i%j>=k)  
			{
				kase++;
//				printf("(%d,%d)\n",i,j);
			}
		}
	}
	printf("%d\n",kase);
	return 0;

}