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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args : Array<String>) {
    val (N, K) = readLine()!!.split(" ").map { it.toLong() }

    var count = 0L
    // Fix b
    (1..N).forEach { b ->
        val p = (N / b)
        val numberOfACandidates = (b - K) * p
        val remainders = N % b
            count += listOf(0, numberOfACandidates).max()!! + listOf(0, remainders - K + 1).max()!!
        if (K == 0L) {
            count--
        }
    }

    println(count)
}