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>
#include<stdlib.h>
#include<string.h>
#include <assert.h>

int main(void){
		long long int a,b;
		long long int c;

		scanf("%lld",&a);
		scanf("%lld",&b);

long long int d = a/b;
		a = a-(d*b);

long long int tmp2;
	while(1){
			tmp2 = llabs(a);
			a = a-b;
			if(tmp2 <=llabs(a)){
				c = tmp2;
				break;
			}
		}



printf("%lld\n",llabs(c));

		return 0;
}