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.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using static System.Console;
class Program
{
	static void Main(string[] args)
	{
		// 整数の入力
		//int a = int.Parse(Console.ReadLine());
		// スペース区切りの整数の入力
		string[] NMK = Console.ReadLine().Split(' ');
		double N = double.Parse(NMK[0]);
		double K = double.Parse(NMK[1]);

		// N > K の時、N%KとKにする
		if(N > K)
		{
			N = N%K;
		}

		// N <= K の時、最小値 = MIN(N, K-N)
		double A = Math.Min(N, K-N);
		// 文字列の入力
		//string s = Console.ReadLine();
		//出力
		//Console.WriteLine((a+b+c) + " " + s);
		Console.WriteLine(A);
	}
}