Problem:
Score : 300 points

Problem Statement

Given any integer x, Aoki can do the operation below.

Operation: Replace x with the absolute difference of x and K.

You are given the initial value of an integer N. Find the minimum possible value taken by N after Aoki does the operation zero or more times.

Constraints

0 ≤ N ≤ 10^{18}

1 ≤ K ≤ 10^{18}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the minimum possible value taken by N after Aoki does the operation zero or more times.

Sample Input 1

7 4

Sample Output 1

1

Initially, N=7.

After one operation, N becomes |7-4| = 3.

After two operations, N becomes |3-4| = 1, which is the minimum value taken by N.

Sample Input 2

2 6

Sample Output 2

2

N=2 after zero operations is the minimum.

Sample Input 3

1000000000000000000 1

Sample Output 3

0

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

n,k = gets.split.map(&:to_i)
a = []
a << (n-k).abs
ans = 0
if k == 1
  ans = 0
else
  1000000000000000000.times do |e|
    a << (a[e]-k).abs
    if a[e-1]<a[e]
      ans = a[e-1]
      break
    elsif a[e-1]==a[e]
      ans = a[e]
    end
  end
end
puts ans