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<iostream>
using namespace std;
int main()
{
    long long int x,y,z,i,j;
    while(cin>>x>>y)
    {
        z=0;
        for(i=1;i<=x;i++)
        {
            for(j=1;j<=x;j++)
            {
                if(i<j&&i>=y){z=z+x-j+1;break;}
                else if(i%j>=y)z=z+1;
            }
        }
        cout<<z<<endl;
    }
    return 0;
}