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.CodeDom.Compiler;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Xml;

class Program
{
	static void Main(string[] args)
	{
		long[] longArray = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();
		long N = longArray[0];
		long K = longArray[1];
		while (true)
		{
			if(N % K == 0)
			{
				N = 0;
				break;
			}
			else
			{
				N = N % K;
				break;
			}

			N = Math.Abs(N - K);

			if(N < K)
			{
				if(N > Math.Abs(N - K))
				{
					N = Math.Abs(N - K);
					break;
				}
			}
		}
		Console.WriteLine(N);
	}
}

//string s = Console.ReadLine();
//int[] intArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
//int H = intArray[0];
//int W = intArray[1];
//int N = int.Parse(Console.ReadLine());
//List<int> A = new List<int>(Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray());
//Boolean ok = false;

//Console.WriteLine(ans);
//Console.WriteLine("Yes");
//Console.WriteLine("No");
//Console.ReadKey();

//string[] strArray = Console.ReadLine().Split(' ').ToArray();
//string S = strArray[0];
//string T = strArray[1];