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;
 
#define FOR(i, n) for(int i = 0; i < (int) n; i++)
#define all(v) v.begin(), v.end()
#define PB push_back
#define F first
#define S second
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
 
const ll MOD = 1e9+7;
 
int main(){
	ios::sync_with_stdio(false); cin.tie(0);
 
	ll n, x; cin >> n >> x;
	cout << min(x-n%x, n%x) << '\n';
 
	return 0;
}