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


class Program
{
    static void Main(string[] args)
    {
        // 入力
        //var s = Console.ReadLine();
        //var n = long.Parse(Console.ReadLine());
        decimal[] nk = Console.ReadLine().Split().Select(decimal.Parse).ToArray();
        var n = nk[0];
        var k = nk[1];

        decimal ans = 0;
        if (n == 0)
        {
            ans = 0;
        }
        else if (n >= k && n % k == 0)
        {
            ans = 0;
        }
        else if (n < k && k % n == 0)
        {
            ans = n;
        }
        else
        {
            ans = Math.Min(Math.Abs((n % k)),Math.Abs((n % k) -k));
        }
        // 出力
        Console.WriteLine(ans);
    }
}