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 Python (3.4.3) (judge verdict: Runtime Error)

import sys

N,K = map(int, input().split())
res = 0
if K==0:
    print(N*N)
    sys.exit(0)
for i in range(N):
    i += 1
    if i-K<=0:
        continue
    amari = N % i
    amari = amari - K + 1
    re = N // i
    if amari <= 0:
        amari = 0
    res += re*(i-K) + amari
 print(res)