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: Time Limit Exceeded)

#include <stdio.h>

int main(){
  long int N,K;
  long int ans;
  long int tmp;
  int flag = 0;
  scanf("%ld %ld",&N,&K);
  
  long int min=N;
  
  while(1){
    N=N-K;
    if(N<0) N*=-1;
    if(N < min) min = N;
    if(N > tmp && flag == 1){
      N=tmp;
      break;
    }
    flag=1;
    tmp = N;
  }
  
  printf("%ld\n",N);
  return 0;
}