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>

using namespace std;
using ll = long long int;
#define vll vector<ll>

#define FOR(i, b, e) for(int i = (b); i < (e); ++i)
#define REP(i, e) FOR(i, 0, e)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
#define OUT(v) cout << (v) << endl;
#define YN(b) OUT((b) ? "YES" : "NO")
#define Yn(b) OUT((b) ? "Yes" : "No")
#define yn(b) OUT((b) ? "yes" : "no")

const ll MOD = 1000000007;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n, k, r = 0;
  cin >> n >> k;
  r = n % k;
  r = min(abs(r - k), r);
  cout << r << endl;

  return 0;
}