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# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class Test
{
    public static void Main()
    {
        //入力
        long[] R = Console.ReadLine().Split().Select(s => long.Parse(s)).ToArray();

        long N = R[0];
        long K = R[1];

        //監視用
        long[] N_ = new long[3];
        N_[0] = 0;
        N_[1] = 0;
        N_[2] = 0;

        long temp = 0;

        while (true)
        {
            N = System.Math.Abs(K - N);

            temp = N_[0];
            N_[0] = N;
            N_[2] = N_[1];
            N_[1] = temp;


            if (N_[0] == N_[2])
            {
                System.Console.WriteLine(N_[1]);
                break;
            }
            else if(N_[0] == N_[1])
                {
                System.Console.WriteLine(N_[1]);
                break;
            }
        }


    }


}