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: Runtime Error)

#include<bits/stdc++.h>
using namespace std;

//x,yを常にx>yにするfunction
/*
void func(int x, int y){
  int z;
  if(x<y){
    z = x;
    x = y;
    y = z;
  }
}
*/

int main(){
  int64_t N;
  int64_t K;
  cin >> N >> K;
  
  //func(N,K);
  int64_t z;
  if(N<K){
    z = N;
    N = K;
    K = z;
  }
  
  bool q = true;
  while(q){
    N = N % K;
    if(N==0){
      break;
    }
    //func(N,K);
    if(N<K){
      z = N;
      N = K;
      K = z;
    }
    
    if(N-K>=K){
      q = false;
    }
  }
  cout << K << endl;
    
}