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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<cstdio>
using namespace std;
long long abs(long long x)
{
	if(x<0)return -x;
	return x;
}
int main()
{
	long long n,k;
	scanf("%lld%lld",&n,&k);
	if(n%k==0)
	{
		printf("0\n");
	}
	else
	{
		n=n%k;
		if(abs(n-k)>abs(n))
		{
			printf("%lld\n",abs(n));
		}
		else
		{
			printf("%lld\n",abs(n-k));
		}
	}
	return 0;
}