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>

int main()
{
  int x,k,n1,n2,p_min;
  int min,p,now;
  scanf("%d",&x);
  scanf("%d",&k);
  
  if(x>k){
    n1 = x; 
    n2 = k;
    p = 0;
  }
  else{
    n1 = k;
    n2 = x;
    p = 1;
  }
  min = x;
  
  if(p==0){
    while(1){
      p_min = min;
      now = n1 - n2;
      min = now;
      n1 = now;
      if(now<=0){
        min *= -1;
        break;
      }
    }
  }
  else if(p==1){
    now = n1 - n2;
    if(min>=now)
      min = now;
  }

  if(p==0){
  	if(p_min < min)
      min = p_min;
  }
  if(min<=x) printf("%d",min);
  else printf("%d",x);
  
  return 0;
}