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: Time Limit Exceeded)

#include <stdio.h>

int main()
{
	long b,N,K;

	scanf("%ld%ld",&N,&K);

	if(K == 1)
	{
		printf("0\n");
		return 0;
	}
	while(N < K)
	{
		N = N / K;
	}
	while(1)
	{
		b = N;
		N = N - K;
		if(N < 0)
		{
			N = N * -1;
		}
		if(b < N)
		{
			N = b;
			break;
		}

	}

	printf("%ld\n",N);
	return 0;
}