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: Time Limit Exceeded)

#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repA(i,a,b) for(int i=a;i<=b;i++)
#define repD(i,b,a) for(int i=b;i>=a;i--)
#define fill(a) memset(a,0,sizeof(a))
#define f first
#define s second
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

int main()
{
    ll n,k;
    cin>>n>>k;
    map<ll,ll>mp;
    ll mn=n;
    while(mp[n]!=1)
    {
        mp[n]=1;
        n=abs(n-k);
        mn=min(mn,n);
    }
    cout<<mn<<endl;
}