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 Go (1.6) (judge verdict: Wrong Answer)

package main

import "fmt"

func main() {
	var n, k int
	fmt.Scan(&n, &k)
	min := 999999999999

	if k == 1 {
		fmt.Println(0)
		return
	}

	for i := 0; i < n/k+30; i++ {
		n = abs(n - k)
		min = Min(min, n)
	}
	fmt.Println(min)
}

func abs(a int) int {
	if a < 0 {
		return a * (-1)
	}
	return a
}

func Min(a, b int) int {
	if a > b {
		return b
	}
	return a
}