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>//llabs関数
int main(void){
  long long n,k;
  scanf("%lld%lld",&n,&k);
  if(n==0){
    printf("%lld",k);
    return 0;
  }
   if(n%k==0){
    printf("0");
    return 0;
  }
  if(n<k&&k-n>=n){
    printf("%lld",n);
    return 0;
  }
  if(n<k){
    long long w=n;
    n=k;
    k=w;
  }
  n=n-(n/k)*k;
  if(n>llabs(n-k))printf("%lld",llabs(n-k));
  else printf("%lld",n);
  
         return 0;
}