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<stdlib.h>

int main(void){

    long long int N,K,i,ans;

    scanf("%lld %lld",&N,&K);

    if(N < K/2){
        //printf("judge1\n");
        ans = N;
    }else if(N < K){
        //printf("judeg2\n");
        ans = abs(N - K);
    }else{
        if(abs(N - (K * (N/K))) < abs(N - (K * ((N/K) + 1)))){
            //printf("judeg3\n");
            ans = abs(N - (K * (N/K)));
        }else{
            //printf("judeg4\n");
            ans = abs(N - (K * ((N/K) + 1)));
        }
    }

    printf("%lld\n",ans);
    return 0;
}