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: Wrong Answer)

#include<iostream>
#include<stdio.h>
#include<string>
#include<cmath>
#include<vector>
#include<algorithm>
#pragma warning(disable: 4996)
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;;
using ll = long long;



int main() {
	ll N, K;
	cin >> N >> K;
	ll ans=N;
	if (N % K == 0) {
		cout << 0 << endl;
		return 0;
	}
	while (ans >= 0) {
		ll x = fabs(K - ans);
		if (x > ans) {
			break;
		}
		else if (x == 0) {
			ans = 0;
			break;
		}
		ans = x;
	}
	cout << ans << endl;
	return 0;
}