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: Accepted)

#include <stdio.h>

int main(void)
{
    long long int N, K;
    long long int temp1, temp2;

    // input
    scanf("%lld %lld", &N, &K);

    temp1 = N % K;
    if (temp1 < 0) {
        temp1 *= -1;
    }
    temp2 = temp1 - K;
    if(temp2 < 0) {
        temp2 *= -1;
    }
    // printf("%lld, %lld\n", temp1, temp2);
    if (temp1 > temp2) {
        printf("%lld\n", temp2);
    } else {
        printf("%lld\n", temp1);
    }
    return 0;
}