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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        int k = sc.nextInt();
        long sabu = 0;
        int cnt = 0;

        long min = Long.MAX_VALUE;

        while(true){
            long num  = Math.abs(n - k);

            if(sabu == n-num){  //(1)絶対値の差が同じ数で連続するなら0に収束
                cnt++;
            }else if(num < min){//最小値の確保
                min = num;
            }else{
                break;
            }

            if(cnt == 3){//(1)で３回連続したら抜ける
                min=0;
                break;
            }
            sabu = n-num;
            n = num;

        }

        System.out.println(min);
    }
}