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("O3", "unroll-loops")
// #pragma GCC target("avx2")

#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds;

typedef long long int ll;
#define endl '\n'
#define ld long double
#define all(a) a.begin(),a.end()
#define int long long
#define pb push_back
#define pii pair <int, int>
#define ff first
#define ss second
#define sz(v) (int)v.size()
#define OST tree<pii, null_type,less<pii>, rb_tree_tag,tree_order_statistics_node_update>

const int INF = 1e15 + 0;
const int mod = 1e9 + 7;
//const int mod = 998244353;

signed main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

    // #ifndef ONLINE_JUDGE
    //   freopen("input.txt", "r", stdin);
    //   freopen("output.txt", "w", stdout);
    // #endif
   int n, k;
   cin >> n >> k;
   int a = n%k;
   cout << min(a, abs(a-k)) << '\n';
}