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 <stdio.h>
#include<string.h>
#include<limits.h>
#include<queue>
#include <cmath>
#include<stack>
using namespace std;
int N,K;

int main()
{
    long  long C1=0;
    scanf("%d %d",&N,&K);
    if(K!=0){

  for(int i=K;i<=N;i++){
    int a=N/i;
    int b=N%i;
    C1+=a*(i-K);
    if(b>=K){
        C1+=b-K+1;
    }
  }
    }if(K==0){
    C1=N*N;
    }
  printf("%lld",C1);


    return 0;
}