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)

#include <iostream>
#include <cstdlib>
 
using namespace std;
 
int main(void)
{
    long long int n, k;
    cin >> n >> k;

    long long int new_n1, new_n2, best = n;
    while(true)
    {
        if (best == 0)
            break;

        new_n1 = abs(best - (best / k) * k);
        new_n2 = abs(best - (k / best) * k);
        if (best > min(new_n1, new_n2))
            best = min(new_n1, new_n2);
        else
            break;
    }

    cout << best << endl;

    return 0;
}