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 PyPy3 (7.3.0) (judge verdict: Accepted)

import sys

def input():
    return sys.stdin.readline()[:-1]

def mi():
    return map(int, input().split())

def ii():
    return int(input())

def main():
    N, K = mi()
    ans = 0
    for b in range(K+1, N+1):
        q = 0
        while K+b*q <= N:
            ans += min((q+1)*b, N+1)-(K+b*q)
            q += 1
    if K == 0:
        ans -= N
    print(ans)


if __name__ == '__main__':
    main()