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: Time Limit Exceeded)

using System;
using System.Linq;

namespace AtCoder
{
    class Program2
    {

        static void Main(string[] args)
        {
            //lee una linea con numeros
            var cantidades = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();

            //separar numeros
            Int64 N = cantidades[0];
            Int64 M = cantidades[1];

            Int64 respuesta = N;
            bool yaesta = false;

            if (M == 1)
                Console.WriteLine("0");
            else
            {
                while (!yaesta)
                {
                    Int64 resta = respuesta - M;
                    Int64 absoluto = Math.Abs(resta);

                    if (absoluto > respuesta)
                        yaesta = true;
                    else
                        respuesta = absoluto;
                }
                Console.WriteLine(respuesta);
            }


        }


    }
}