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: Time Limit Exceeded)

# coding: utf-8
init = [int(s) for s in input().rstrip().split(' ')]

if init[1] == 1:
    print(0)
elif init[1] == 0:
    print(init[0])
elif init[0] % init[1] == 0 and init[0] > init[1]:
    print(0)
elif init[0] == init[1]:
    print(0)
else:
    count = 0
    tmp = init[0]
    minX = tmp + 10
    preMinX = tmp + 10
    while count < 100:
        tmp = abs(tmp - init[1])
        minX = min(minX,tmp)

        if minX == 0 or preMinX == tmp:
            print(tmp)
            break
        else:
            preMinX = minX

    if count > 100:
        print(tmp)