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)

s=input().split()

N=int(s[0])
K=int(s[1])

if N > K/2 and N < K:
    print(abs(N-K))

if N <= K/2:
    print(N)

if N==K:
    print(0)

while N > 1000*K:
    N=N-1000*K
    if N <=1000*K:
        break

while N > 100*K:
    N=N-100*K
    if N <=100*K:
        break

if N > K:
    while N > K:
        N=N-K
        if N <= K:
            break

    if N > K/2 and N < K:
        print(abs(N-K))

    if N <= K/2:
        print(N)

    if N==K:
        print(0)