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.Text;

namespace atCoder161
{
    class ClassC
    {
        static void Main(string[] args)
        {
            string[] str = Console.ReadLine().Split(' ');

            long N = long.Parse(str[0]);
            long K = long.Parse(str[1]);

            long min = N;
            long zettai = N;

            while(true)
            {
                zettai = Math.Abs(N - K);
                if (zettai < min)
                {
                    min = zettai;
                }else if( zettai == min)
                {
                    break;
                }

            }
            
            Console.WriteLine(min);
        }
    }
}