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 C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>

long long gcd(long long a,long long b){long long r,tmp;if(a < b){tmp = a;a = b;b = tmp;}r = a % b;while(r != 0){a = b;b = r;r = a % b;}return b;}
long long lcm(long long a,long long b){long long r;r = gcd(a,b);r = a / r * b;return r;}

int main()
{
    long long n,k;

    scanf("%lld %lld",&n,&k);

    printf("%lld",gcd(n,k));
}