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 (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<math.h>

void main(){
  int i=0;
  long long int n, k, x[3], xmin;
  scanf("%lld %lld", &n, &k);
  
  x[0] = abs(n-k);
  x[1] = abs(x[0]-k);
  x[2] = abs(x[1]-k);
  while(x[i%3]!=x[(i+2)%3]){
//    printf("%lld %lld %lld\n",x[0],x[1],x[2]);
    x[i%3] = abs(x[(i+2)%3]-k);
    i++;
  }
  xmin = x[0];
  if(xmin>x[1])
    xmin = x[1];
  if(xmin>x[2])
    xmin = x[2];
  
  printf("%lld",xmin);
}