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 long a,b,c,i,j,k;
    scanf("%lld%lld",&a,&b);
    if(a>b)
    {
    	if(a%b==0)
    	a=0;
    	else
    	{
    		for(i=0;1;i++)
    		{
    			a=a-b;
    			if(a<0)
    			break;
			}
			a=-a;
			a=(b-a)>a?a:(b-a);
		}
	}
    else
    {
    	a=(b-a)>a?a:(b-a);
	}
    printf("%lld",a);
    return 0;
}