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;

#define SORT(c) sort((c).begin(), (c).end())
#define REVERSE(v) reverse((v).begin(), (v).end())
#define ANS(ans) cout << (ans) << endl;
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end());
typedef vector<int> VI;
typedef pair<int, int> P;

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define REP(i, n) for (long long i = 0; i < (n); ++i)

int main() {
  ll n, k;
  cin >> n >> k;

  ll ans = n;
  ans = min(ans, n % k);
  ans = min(ans, abs(n % k - k));

  ANS(ans);
  return 0;
}