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: Accepted)

#include <iostream>
#include <string>
#include <cstdint>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <climits>
#include <numeric>
#include <algorithm>
#include <cassert>

using namespace std;


int main()
{
    int64_t n,k;
    cin >> n >> k;
    
    for(;;){
        if(n == k){
            cout << "0\n";
            return 0;
        }
        else if(n < k){
            cout << min(n, k-n) << '\n';
            return 0;
        }
        else {
            n = n % k;
        }
    }
    return 0;
    /*
    n
    |n-k|
    ||n-k|-k|
    |||n-k|-k|-k|
    
    n == ||n-k|-k|
    
    n = k　のとき  
      k,0,k,0,...
    
    n < k のとき
      n, k-n, n, k-n, ...
 
    n > k のとき
    
    n, n-k
    */
    
    return 0;
}