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>

#define pb push_back
#define sp " "
#define fi first
#define se second
#define mp make_pair
#define sz(a) ((int)a.size())
#define tra(a,b) for (auto a:b) 
#define fo(a,b,c) for (unsigned long long a=b;a<=c;a++) 
#define ms(a,b) memset(a,b,sizeof(a)) 
#define all(a) a.begin(),a.end()
#define rev(a) reverse(a.begin(),a.end())
#define bit(i,j) (i&(1<<j))
using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
typedef pair<int,ii> iii;

const int N=2e5+5,mod=998244353;
ll a,b;

int main()
{
	cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
	cin>>a>>b;
	if (a<=1 || b==1) { cout<<0; return 0; }
	cout<<__gcd(a,b);
	return 0;
}