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 <chrono>

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <bitset>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <cmath>
#include <time.h>
#include <random>
#include <string>
#include <cassert>
#include <vector>
#include <ostream>
#include <istream>
#include <stack>
#include <deque>
#include <queue>
#include <functional>

using namespace std;

#define int long long
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define pii pair<int, int>
#define ld long double

ostream& operator << (ostream &a, const vector<int> &b) {
    for (auto k : b) cout << k << " ";
    return a;
}

#ifdef LOCAL
    #define dbg(x) cout << #x << " : " << (x) << "\n";
    const int INF = 1e18;
//    const int mod = 2600000069;
//    const int p = 10;
//    const ld PI = 3.1415926535;
#else
    #define dbg(x)
    const int INF = 1e18;
//    const int mod = 2600000069;
//    const int p = 179;
//    const ld PI = 3.1415926535;
#endif

//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,sse3,sse4")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("fast-math")
//#pragma GCC target("avx2")
//#pragma GCC optimize("section-anchors")
//#pragma GCC optimize("profile-values,profile-reorder-functions,tracer")
//#pragma GCC optimize("vpt")
//#pragma GCC optimize("rename-registers")
//#pragma GCC optimize("move-loop-invariants")
//#pragma GCC optimize("unswitch-loops")
//#pragma GCC optimize("function-sections")
//#pragma GCC optimize("data-sections")

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    #ifdef LOCAL
    #else
//        freopen("capitals.in", "r", stdin);
//        freopen("capitals.out", "w", stdout);
    #endif
    int n, k;
    cin >> n >> k;
    set<int> cur;
    cur.insert(n);
    n %= k;
    for (int i = 0; i < 100; i++) {
        cur.insert(abs(n - k));
        n = abs(n - k);
    }
    cout << *cur.begin();
}
/*
*/