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: Accepted)

#include<stdio.h>

long int longabs(long int); //ライブラリにあるabsはint型を受け取る関数

int main(){
  long int min=100,x,n,k;
  int i;
  scanf("%ld %ld",&n,&k);
  
  if(longabs(n-(n/k)*k)>longabs(n-((n/k)+1)*k))
    printf("%ld",longabs(n-((n/k)+1)*k));
  else
    printf("%ld",longabs(n-(n/k)*k));
}

long int longabs(long int a){
  if(a<0)
    return -a;
  else
    return a;
}