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;

typedef long long ll;
typedef unsigned long long ull;
using P = pair<ll, ll>;
using V = vector<ll>;
#define rep(i, n) for(ll i=0;i<(ll)(n);i++)
#define rep1(i, n) for(ll i=1;i<=(ll)(n);i++)
#define rep2(i, m, n) for(ll i=m;i<(ll)(n);i++)
#define rrep(i, n, m) for(ll i=n;i>=(ll)(m);i--)
#define ALL(obj) (obj).begin(), (obj).end()
#define MOD 1000000007
#define INF 1000000000

void solve_abc() {
	ll n, k;
	ll ans = 0;

	cin >> n >> k;

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

	cout << ans << "\n";
}

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

	solve_abc();

	return 0;
}