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.chomp.split(' ').map{|n| n.to_i}

sum = 0
if(K==0)
	puts N*N
	exit(0)
end
K.upto(N){|b|
	q = N/b
	r = N-q*b-(K-1)
	r = 0 if r < 0
	dif = (b-(K))*q + r
	sum += dif
	# puts "bqr #{b}, #{q}, #{r}, sum+=#{dif}"
}
puts sum