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 Python (3.4.3) (judge verdict: Runtime Error)

def main():
  n,k = map(int, input().split())
  
  if k == 1:
    return 0
  
  result = check(n, k, [n])
    
  return result

def check(val1, val2, checked):
  tmp = val1 - val2 if val1 - val2 > 0 else val2 -val1
  if tmp == 0:
    return 0
  if tmp in checked:
    return min(checked)
  checked.append(tmp)
  return check(tmp, val2, checked)
  
print(main())