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(){
  long long int n, k, x, xmin;
  int logx, logk;
  scanf("%lld %lld", &n, &k);
  logk = log(k);
  
  x = n-k; 
  while(x>0){
    logx = log(x);
    if(logx>logk)
      x -= pow(10,logx-logk)*k;
    else
      x -= k;    
  }
  x = abs(x);
  while(x>0){
    x -= k;    
  }
  x = abs(x);
  xmin = abs(x-k);
  x = abs(xmin-k);
//  printf("%lld %lld\n", x, xmin);
  if(xmin>x)
    xmin = x;
  
  printf("%lld",xmin);
}