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 <algorithm>
//#include <cstdio>
//#include <functional>
#include <iostream>
//#include <cfloat>
//#include <climits>
//#include <cstdlib>
//#include <cstring>
//#include <cmath>
//#include <map>
//#include <queue>
//#include <set>
//#include <sstream>
//#include <stack>
//#include <string>
//#include <time.h>
//#include <vector>
//#include <random>
//#include <unordered_set>
//#include <complex>
#define WAIT system ("pause")
#define rt0 return 0
using namespace std;
int main()
{
 //   WAIT; 

 int N,K;
 int count=0;
 cin>>N>>K;

if(K==0) {
	cout<<N*N;
	rt0;
}
for(int j=K+1; j<=N;j++)
{
	count+=((N/j)*(j-K));
	int t=N%j;
	if(t>0)	count+=max(0,t-K+1);
}

cout<<count;
    rt0;
}