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>
#include <unordered_set>
#include <unordered_map>
#include <exception>

using namespace std;

typedef long long ll;
typedef long long ull;
typedef pair<int, int> ii;

#define all(v)		((v).begin()), ((v).end())
#define sz(v)		((int)((v).size()))
#define endl		"\n"
#define fx(n)		fixed<<setprecision(n)
#define mk			make_pair	

void fast()
{
	ios::sync_with_stdio(NULL);
	cout.tie(NULL);
	cin.tie(NULL);
}
void File()
{
	#ifndef ONLINE_JUDGE
	freopen("output.txt", "w", stdout);
	freopen("input.txt", "r", stdin);
#endif
#ifdef ONLINE_JUDGE
	/*freopen("output.txt", "w", stdout);
	freopen("pyramid.in", "r", stdin);*/
#endif
}
const double pi = 2 * acos(0.0);
const ll oo = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const int nn = 1e5 + 15;
int dx[8] = { 1, -1, 0, 0, 1, -1, 1, -1 };
int dy[8] = { 0, 0, 1, -1, 1, -1, -1, 1 };

int main()
{
	fast();
	//File();
	ll a,b;
	cin>>a>>b;
	if(a%b==0)
		return cout<<0<<endl,0;
	ll diff=abs(a-b);
	cout<<a%min(diff,b)<<endl;
	return 0;
}