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: Runtime Error)

using System;

using System.Linq;

using System.Collections.Generic;



namespace hello_cs

{

    class Program

    {

        static void Main(string[] args)

        {

            var blank = "";

            var ipt = Console.ReadLine().Split(blank.ToCharArray()).Select(x => int.Parse(x));

            var n = ipt.First();

            var k = ipt.Last();



            var num = new  List<int>();

            while (!num.Contains(n))

            {

                num.Add(n);

                n = Math.Abs(n - k);

            }

            num.Sort((a,b) => a - b);

            System.Console.WriteLine(num[0]);

        }

    }

}