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>
#include<assert.h>

#define max(a,b) ((a)>(b))?(a):(b)
#define min(a,b) ((a)>(b))?(b):(a)

typedef long long ll;
typedef unsigned long long ull;

int main(void)
{
    ll n, k;
    scanf("%lld%lld", &n, &k);
    
    if (n==0)
    {
        printf("0");
    }
    else
    {
        ll res = n % k;
        if (res <= abs(k - res))
        {
            printf("%d", res);
        }
        else
        {
            printf("%d", abs(k - res));
        }
    }
}