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 (2.7.1) (judge verdict: Accepted)

attrs = Array.new
while line = $stdin.gets
  attrs << line.chomp.split
end

N, K = attrs[0].map{|a| a.to_i}

if N%K ==0 then
  puts 0
elsif N < K then
  a = N
  b = K-N
  puts [a,b].min
elsif N < 2*K then
  a = 2*K-N
  b = N-K
  puts [a,b].min
else
  n = N - (N/(2*K)).to_i * 2 * K
  if n < K then
    a = n
    b = K-n
    puts [a,b].min
  else
    a = 2*K-n
    b = n-K
    puts [a,b].min
  end
end