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: Time Limit Exceeded)

#include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <vector>
#include <string>
#define rep(i, n) \
    ;             \
    for (int i = 0; i < (n); i++)
using namespace std;

int main()
{
    long long n, k, t;
    bool check = true;
    cin >> n >> k;
    t = n;
    long long i = 0;
    if (n % k == 0)
    {
        cout << 0;
    }
    else
    {
        while (check)
        {
            n = abs(n - k);
            if (t <= n)
            {
                check = false;
            }

            t = min(t, n);
        }
        cout << t;
    }
}