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: Wrong Answer)

#include <bits/stdc++.h>
#include <algorithm>
#define rep(i, n) for (int i=0; i<n; ++i)
#define all(obj) (obj).begin(),(obj).end()
using namespace std;
typedef long long ll;

int main(){
    ll N, K; cin >> N >> K;
    if(N<K){
      cout << N << endl;
      return 0;
    }
    else{
    if(N%K==0){
        cout << 0 << endl;
        return 0;
    }
    int x = N / K;
    int ans = min(abs(N-K*x), abs(N-K*(x+1)));
    cout << ans << endl;
    return 0;
    }
}