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() }
    if(K == 0L){
        println(N * N)
        return
    }
    var ans = 0L
    for(b in 1..N){
        val div = N / b
        val rem = N % b
        ans += div * (Math.max(0, b - K))
        ans += Math.max(0, rem - K + 1)
    }
    println(ans)
}