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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
int zettaiti(int a,int b){
  int c;
  c = a-b;
  if(c>=0){
    return c;
  }
  else {
    return -c;
  }
}
  
int main() {
  long long N;
  int K;
  cin >> N >> K;
  int ans = N;
  //cout << N << endl;
  //cout << zettaiti(N ,K) <<endl;
  for (int i=0;i<1000000000000000000;i++){
    if (K==1){
      ans = 0;
      break;
    }
    N = zettaiti(N,K);
    if (N < ans){
      ans = N;
    }
    if (N == ans) break;
  }
  cout << ans <<endl;
}