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 <bits/stdc++.h>

#define REP(i, x, n) for (int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x.size())
#define popcount(x) __builtin_popcount(x)
#define popcountll(x) __builtin_popcountll(x)
#define uniq(x) x.erase(unique(x.begin(), x.end()), x.end())
#define F first
#define S second
#define mp make_pair
#define eb emplace_back
#define pii pair<int, int>
#define pll pair<ll, ll>

using namespace std;

typedef long long ll;

/* --- INFやMODの値が適切か確認する --- */
// const int INF = 1 << 30;
// const ll INF = 1LL << 60;
// const ll MOD = 1000000007;

int main() {
  ll n, k;
  cin >> n >> k;
  n %= k;
  n = min(n, abs(n - k));
  cout << n << endl;
}