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: Wrong Answer)

#include <stdio.h>
#include <math.h>

int min(int x, int y){
    if(x < y){
        return x;
    }else{
        return y;
    }
}

int main(int argc, char const *argv[])
{
    int n,k;
    scanf("%d %d",&n,&k);

    if(k == 1){
        printf("%d",0);
    }else if(n % k == 0 && n > k){
        printf("%d",0);
    }else if(n == k){
        printf("%d",0);
    }else{
        int i,minx,premin,tmp;
        tmp = n;
        minx = n;
        premin = n;

        for(i=0;i < 100;i++){
            tmp = fabs(tmp - k);
            minx = min(minx,tmp);
            if(minx == 0 || premin == tmp){
                printf("%d",tmp);
                return 0;
            }else{
                premin = minx;
            }
        }
    }
    return 0;
}