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 <algorithm>
#include <numeric>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <functional>
using namespace std;
#define int long long
#define All(v) (v).begin(),(v).end()
int dy[8] = {-1,0,1,0,-1,1,1,-1};
int dx[8] = {0,1,0,-1,1,1,-1,-1};
const int mod = 1000000007;
const int inf = mod*mod;
const int d5 = 100100;

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n,k;
    cin>>n>>k;
    if(n>=k){
        if(n%k==0)cout<<0<<endl;
        else{
            n-=n/k*k;
            cout<<min(n,k-n)<<endl;
        }
    }else{
        cout<<min(n,k-n)<<endl;
    }
}