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(){
    // Your code here!
    var n, k int64
    fmt.Scan(&n, &k)
    var t = n
    n = n - ((n / k) * k)
    for ;;{
        n = abs((n-k))
        if n >= t{
            fmt.Println(t)
            return
        }
        t = n
        
    }
   
}

func abs(v int64) int64{
    if v < 0{
        return -v
    }else{
        return v
    }
}