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: Wrong Answer)

list_NK = list(map(int, input().split())) 
N = list_NK[0]
K = list_NK[1]
i = 0
abs_list = []
abs_list.append(N)
while all:
    abs_list.append(abs(abs_list[i] - K))    
    if(abs_list[i+1]>=abs_list[i]):
        break
    i += 1
print(abs_list[len(abs_list)-1])