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: Accepted)

#include <stdio.h>

unsigned long long int ZET(unsigned long long int N, unsigned long long int K)
{
    if (N > K)
    {
        return N-K;
    }

    if (N <= K)
    {
        return K-N;
    }
    
    
}
 
int main(void)
{
    unsigned long long int N, K;
    scanf("%llu %llu", &N, &K);

    if (N > K)
    {
        N = (N%K) + K;
    }
    

    while (ZET(N,K) < N)
    {
        N = ZET(N,K);
    }

    printf("%llu", N);
    
    


    return 0;
}