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()
{
  int N,K,i,j;
  int c=0;
  scanf("%d %d",&N,&K);
  if(K>0){
    for(i=K;i<=N;++i){
      for(j=1;j<=i;++j){
        if(i%j>=K) ++c;
      }
      for(j=i+1;j<=N;++j) ++c;
    }
  }
  else{
    for(i=K+1;i<=N;++i){
      for(j=1;j<=i;++j){
        if(i%j>=K) ++c;
      }
      for(j=i+1;j<=N;++j) ++c;
    }
  }
  printf("%d\n",c);
  return 0;
}