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>



int main (void)
{
    unsigned long long n,k;
    unsigned long long diff;
    unsigned long long diffmin;
    scanf("%llu %llu",&n,&k);
    diff=llabs(n);
    diffmin=llabs(diff);
    diff=diff%k;
    if (diffmin>diff)
    {
    diffmin=diff;

    for(;;)
    {
        diff=llabs(diff-k);

        if (diffmin>diff)diffmin=diff;
        else break;

    }
    }

    printf("%llu",diffmin);
}