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>
using namespace std;
#define rep(i,n) for(int i=0; i<(n) ;i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define sz(x) ((int)(x).size())
using ll=long long;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define MOD  1000000007
const ll INF=1e18;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b){ a = b; return 1; } return 0; }



int main(int argc, char const *argv[]) {
  ll n,k; cin >> n >> k;
  if(k==1){
    cout << "0" << endl;
  }
  else if(n<k){
    cout << n << endl;
  }
  else{
    cout << min(n%k,abs(n%k-k)) << endl;
  }

  return 0;
}