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.Linq;
class Ho{
  static void Main(){
    var zennbu = Console.ReadLine().Split();
    var N = long.Parse(zennbu[0]);
    var K = long.Parse(zennbu[1]);
    var j = 0;
    if(K > N){
      Console.WriteLine(N);
    }
    else if(N == K){
      Console.WriteLine(j);
    }
    else{
      long amari = N%K;
      long saidai = (N-amari)/K;
      long kotae1 = N-(saidai*K);
      
      long kotae2 = -1*(kotae1 - K);
      if(kotae1 <= kotae2){
        Console.WriteLine(kotae1);
      }
      else{
        Console.WriteLine(kotae2);
      }
    }

    
   
  }
}