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: Wrong Answer)

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

int main(){
  unsigned long long n,k,r,q,t;
  unsigned long long min;

  scanf("%llu %llu", &n, &k);

  q = 1;

  if(k != 0){
    r = n/k;
    q = n % k;
  }

  if(q == 0 && k != 0) printf("0\n");

  else if(q == 1 && k == 0) printf("%llu", n);

  else{
    min = abs(n - r*k);
    t = abs(min - k);

    if(min > t) printf("%llu\n", t);

    else printf("%llu\n", min);
  }

  return 0;
}