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 Go (1.6) (judge verdict: Accepted)

///
// File:  d.go
// Author: ymiyamoto
//
// Created on Sun Mar 11 21:36:29 2018
//
package main

import (
	"fmt"
)

var N, K int

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func main() {
	fmt.Scan(&N, &K)

	count := 0
	for b := 1; b <= N; b++ {

		count += (N/b)*max(0, b-K) + max(0, (N%b)-K+1)
		if K == 0 {
			count--
		}
	}

	fmt.Println(count)
}