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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int compare_int(const void *a, const void *b)
{
	return *(int *)b - *(int *)a;
}

int main(void)
{
	int i, j, k;
	int ii[1000];
	int min, max;
	int len, flg;
	long long cnt=0, maxcnt;
	long long N,K;
  scanf("%lld %lld", &N,&K);
	if(N<K){
      printf("%lld\n",N);
      return 0;
    }
	if(N==K){
      printf("0\n");
      return 0;
    }
  cnt = N%K;
	if(K>cnt*2){
  printf("%lld\n",cnt);
    }
  	else{
  printf("%lld\n",K-cnt);
    }
      return 0;
}