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

public class Coder
{

    public static int[] ReadArray()
    {
        return Array.ConvertAll(Console.ReadLine().Split(' '), m => Convert.ToInt32(m));
    }

    public static int ReadInt()
    {
        return Convert.ToInt32(Console.ReadLine());
    }

    public static string ReadStr()
    {
        return Console.ReadLine();
    }

    public static long ReadLong()
    {
        return Convert.ToInt64(Console.ReadLine());
    }

    public static long[] ReadLongArray()
    {
        return Array.ConvertAll(Console.ReadLine().Split(' '), m => Convert.ToInt64(m));

    }

    public static void Main()
    {

        long[] A = ReadLongArray();

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

        long n = N % K;
        Console.WriteLine(Math.Min(n,Math.Abs(n-K)));

        
    

    }

}