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 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <limits.h>
 
int main()
{
  long int nn, kk, min = LONG_MAX;
  scanf("%ld %ld", &nn, &kk);
  long int old_nn = nn;
  if(nn > kk)
    nn = kk + (nn % kk);
  while(nn < min)
  {
    old_nn = nn;
    min = nn;
    if(nn > kk)
      nn = nn -kk;
    else if(kk > nn)
      nn = kk -nn;
    else
    {
      old_nn = 0;
      break;
    }
  }
  printf("%ld\n", old_nn);
  return 0;
}