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: Accepted)

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

c=abs(n-k)
d=abs(c-k)
if(c+d==k):
    if(c>d):
        print(d)
    else:
        print(c)
    exit()
if(n>=k):
    if(n%k==0):
        print(0)
        exit()
    else:
        a=n-k*(n//k)
        b=k*(n//k+1)-n
        if(a>b):
            print(b)
        else:
            print(a)
        exit()
else:
    
    while(1):
        a=abs(n-k)
        if(n>a):
            n=a
        else:
            print(n)
            exit()