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 Ruby (2.3.3) (judge verdict: Accepted)

n,k=gets.split
n=n.to_i
k=k.to_i

b=k+1
ans=0
key=1
aa=0
bb=0

if k==0
    puts n**2
    exit
end
(n-b+1).times{
    
    aa=n/b

ans+=key*aa
 bb=b*aa+k
 
 ans+=[n-bb+1,0].max
   
   key+=1
   b+=1
   
}



puts ans