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 (Clang 3.8.0) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

long chan(long a, long b)
{
    if (a > b)
    {
        return a - b;
    }
    else
        return b - a;
}


int main()
{
    long a, b,c;
    scanf("%ld %ld", &a, &b);
    if(b==1){
        a = 1;
    }
    else if (a>chan(a, b)){
        while (1)
        {
            if (a > b)
            {
                c= a - b;
            }
            else{
                c= b - a;
                if(c>=a)
                    break;
            }
                a = c;
        }
    }

    if(a==b)
        a = 0;
    printf("%ld\n", a);
}