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: Runtime Error)

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

namespace task3
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] input = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int N = input[0];
            int K = input[1];
            if (K == 1)
                Console.WriteLine("0");
            else
            {
                while (Absolute(N-K) > Absolute(Absolute(N-K)-K))
                {
                    N = Absolute(N - K);
                }
                N = Absolute(N - K);
                Console.WriteLine(N);
            }
        }
        static int Absolute(int v)
        {
            if (v < 0)
                return -v;
            return v;
        }
    }
}