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++14 (GCC 5.4.1) (judge verdict: Accepted)

//...Bismillahir Rahmanir Rahim...
// Code by    Asad Bin Saber
// 04 04 2020

#include <stdio.h>
#include <string.h>
#include <vector>
#include <algorithm>
#include <math.h>
#include <iostream>

using namespace std;

void task()
{
    long long n, k, i;

    cin>>n>>k;

    n = n % k;

    while(1){
        if(n==0) break;
        else if(n<abs(k-n)) break;
        n = abs(n-k);
    }

    cout<<n<<endl;
}

int main()
{
    task();

    return 0;
}