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 <algorithm>
#include <array>
#include <deque>
#include <functional>
#include <iostream>
#include <math.h>
#include <numeric>
#include <vector>
#define ll long long int
#define FOR(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
#define REP(i, n) FOR(i, 0, n)
#define REP1(i, n) FOR(i, 1, n)

using namespace std;

int main() {
    ll n, k;
    cin >> n >> k;
    // ll ans = n;
    // if (n == 1 || k == 1 || n == k || n % k == 0) {
    //     cout << 0 << endl;
    // } else {
    //     if (n > 2 * k) {
    //         n = n / k;
    //     }
    //     cout << min(abs(n - k), abs(abs(n - k) - k)) << endl;
    // }
    n = n % k;
    cout << min(abs(n - k), abs(abs(n - k) - k)) << endl;
    return 0;
}