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>

typedef unsigned long long int ulli;

int main(void)
{
	ulli N, K;
	scanf("%d %d", &N, &K);
	ulli i;
	for (i = 1; i>=0; i++) {
		if (i * K >= N) {
			if ((2 * i - 1) * K >= 2 * N) {
				printf("%llu", N - (i - 1) * K);
				break;
			}
			else {
				printf("%llu", i * K - N);
				break;
			}
		}
	}

	return 0;
}