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 main() 
{ 
    long long a, b;
    cin >> a >> b;
    if(b == 1) {
        cout << 0 << "\n";
    } else {
        if(a > b) {
            cout << __gcd(a,b) << "\n";
        } else if(a == b){
            cout << 0 << "\n";
        } else {
            if(__gcd(a,b) == 1) {
                cout << a << "\n";
            } else {
                cout << __gcd(a,b) << "\n";
            }
        }
    }
    return 0;
}