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: Accepted)

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

public class MainApp
{

	static public void Main()
	{

		long[] NK = Arrayint();

		long ans1 = NK[0] % NK[1];
		long ans2 = NK[1] - ans1;
		long ans = 0;
		if(ans1 > ans2)
		{
			ans = ans2;
		}
		else
		{
			ans = ans1;
		}

		Console.WriteLine(ans);
	

	}


	private static string[] Arraystring()
	{
		return Console.ReadLine().Split(' ');
	}

	private static string Onestring()
	{
		return Console.ReadLine();
	}

	private static int Oneint()
	{
		return int.Parse(Console.ReadLine());
	}

	private static long[] Arrayint()
	{
		return Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
	}
}