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 <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <cctype>
#include <cassert>
#include <cstring>
#include <climits>
 
using namespace std;
 
#define FOR(k,a,b) for(int k=(a); k < (b); k++)
#define FORE(k,a,b) for(int k=(a); k <= (b); k++)
#define REP(k,a) for(int k=0; k < (a); k++)
 
#define ALL(c) (c).begin(), (c).end()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define RANGE(lb, x, ub) ((lb) <= (x) && (x) < (ub))
 
#define dump(x) cerr << #x << ": " << (x) << endl;
 
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
 
const int INF = 1000000000;
const double EPS = 1e-10;
const double PI = acos(-1.0);
 
int main(void) {
	ll n, k; cin >> n >> k;
	ll m = n % k;
	ll res = min(m, abs(m - k));

	cout << res << endl;

    return 0;
}