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 <bits/stdc++.h>
using namespace std;

int main() {

    int n,k;

    cin >> n >> k;

    if(k==0){
        cout << n*n << endl;
        return 0;
    }

    long long int ans = 0;

    for(int b=k+1; b<=n; b++){
        int tmp = n/b;
        ans += max(0,tmp*(b-k));
        if(n%b>=k) {
            ans += max(0, n % b - k + 1);
        }
    }



    cout << ans << endl;


    return 0;
}