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 <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <cmath>
#include <iomanip>
#include <queue>
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
int main(void){
    int n,k,p,r,cnt = 0;
    cin >> n >> k;
    if(k == 0){
        cout << n*n << endl;
        return 0;
    }
    for(int b = 1;b <= n;b++){
        r = (n%b);
        p = (n/b);
        cnt += (p*max(b-k,0)+max(r+1-k,0));
    }
    cout << cnt << endl;
    return 0;
}