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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>



int main(void){
    int N,K;
    scanf("%d %d",&N,&K);
    long long int ans=0;
    if(K!=0){
    for(int i=K+1;i<=N;i++){
        int po=(N+1)%i;
        if(po>=K)ans+=po-K;
        int buri=(N+1)/i;
        ans+=buri*(i-K);
        //printf("%lld\n",ans);
    }
    printf("%lld",ans);
    }
    else {
        ans=N*N;
        printf("%lld",ans);
    }
    return 0;
}