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.Collections.Generic;
using System.Linq;

public class Hello{
    public static void Main(){
        var input = Console.ReadLine().Split(' ').Select(x=>Int64.Parse(x)).ToList();
        var n = input[0];
        var k = input[1];
        var x1 = n;
        
        if(k < n){
            x1 = n % k; 
        }
        
        if(x1 == 0){
            Console.WriteLine(x1);
            return;
        }
        
        var x2 = Math.Abs(x1 - k);
        
        if(x1 < x2){
            Console.WriteLine(x1);
            return;
        }
        
        Console.WriteLine(x2);
        return;
    }
}