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>

int main(void)
{
    long long n,k;
    long long t=0;
    long long ans=0;

    scanf("%lld %lld",&n,&k);
    // printf("n=%lld k=%lld\n",n,k);

    t=n%k;
    // printf("t=%lld\n",t);

    if (t==0){
        ans=0;
    }else if (n<k){
        if ((k-n)<n)
            ans=k-n;
        else
            ans=n;
    }else{
        ans=k-t;
    }  
    
    printf("%lld\n",ans);


}