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: Accepted)

package main

import "fmt"

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

func main() {
  var N, K, count int
  fmt.Scan(&N, &K)
  Nmin := N
  N = N%K
  
  for {
    N = abs(N-K)
    if N < Nmin {
      Nmin = N
      count = 0
    }
    if Nmin == N{
      count++
      if count >1 {
        break
      }
    }
  }
  fmt.Println(Nmin) 
}