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;

namespace ConsoleApp10
{
    class Program
    {
        public static void Main()
        {
            string input = Console.ReadLine();
            string[] inputA = input.Split(' ');
            long N = long.Parse(inputA[0]);
            long K = long.Parse(inputA[1]);
            if (K <= 1)
            {
                Console.WriteLine("0");
                return;
            }
            var NTemp = N;
            int c = 0;
            for (int i = 0; ; i++)
            {
                NTemp -= K;
                if (NTemp  < 0)
                {
                    break;
                }
                c++;
            }

            var NAbs = Math.Abs(NTemp);
            if (c == 0)
            {
                Console.WriteLine(N);
            }
            else
            {
                Console.WriteLine(NAbs);
            }
        }
    }
}