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 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int main(void)
{
	long n,k,copy;
	int i;

	scanf("%ld %ld",&n,&k);

	copy=n;
	if(k==1){
		puts("0");
		return 0;
	}
	if(k<=10){
		copy=n%k;
		printf("%ld",copy);
	}

	while(1){
		if(copy-k<=0) break;
		copy-=k;
	}

	if(copy<k-copy){
		printf("%ld\n",copy);
	}
	else printf("%ld\n",k-copy);

	return 0;
}