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: Wrong Answer)

N,K = [int(x) for x in input().split()]
ans =0
for i in range(K+1,N+1):
  #print((N//i)*(i-K),N%i+1-K)
  ans += (N//i)*(i-K)
  if N%i!=0 and K!=0:
    ans +=(N%i+1-K)
  elif N%i!=0 and K==0:
    ans +=(N%i)
print(ans)