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 PyPy3 (2.4.0) (judge verdict: Accepted)

#!/usr/bin/env python3

n, k = map(int, input().split())

if n == 0 or n == k:
    print(0)
elif k == 1:
    print(0)
else:
    if n > k:
        r = n % k
        if r == 0:
            print(0)
        else:
            n_1 = abs(r - k)
            n_2 = abs(n_1 - k)
            print(min(n_1, n_2))
    else:
        n_1 = abs(n - k)
        n_2 = abs(n_1 - k)
        print(min(n_1, n_2))