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>
#define MOD 100000007
#define PI 3.141592653589793238
#define pb push_back
#define ALL(V) (V).begin(), (V).end()
#define rep(i, a, b) for(int i = (a); i < (b); ++i)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long long int lint;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
inline ll gcd(ll a, ll b) { return (a % b == 0 ? b : gcd(b, a % b)); }
inline ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
inline ll char_to_ll(char c) { return (int)(c - '0'); }
inline ll string_to_ll(string s) { return atoi(s.c_str()); }
inline bool is_prime(ll x){ if(x <= 1) return false; for(ll i = 2; sqrt(i) <= x; i++) if(x % i == 0) return false; return true; }

int main(){
    ll N, K;
    cin >> N >> K;

    N %= K;

    if(abs(N - K) < N) N = abs(N - K);

    cout << N << endl;

    return 0;
}