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)

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
typedef long long ll;
#define rep(i,n) for (int i = 0; i < (n); i++)
#define repe(i,n) for (int i = 0; i <= (n); ++i)
#define repe1(i,n) for (int i = 0; i <= (n); ++i)
#define all(x) (x).begin(),(x).end()
#define pb(x) push_back(x)
#define eb(k,v) emplace_back(k,v)
#define ct(res) cout << res << "\n";
#define vi vector<int>
#define vl vector<ll>
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const int INF = 1e9;
const ll MOD = 1000000007;
using Graph = vector<vector<int>>;

int func(ll a, ll k) {
    ll a1 = a;
    ll a2 = k;
    ll diff = abs(a-k);
    swap(a,diff);
    a = diff - k;
    if (a1 == a && a2 == diff) {
        return min(a,diff);
    }
    func(a, k);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll n,k; cin >> n >> k;
    ll ans = min(n%k, k-n%k);
    ct(ans);
}