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;
#define lld long long int
#define M 1000000007
#define fors(i,n) for(int i=0;i<n;++i)
#define fore(i,a,b) for(int i=a;i<=b;++i)
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define vv vector<int>
#define endl "\n"
#define test(i) cout<<i<<endl
#define itrt int t; cin>>t; fors(i,t)
#define itr1 int t; cin>>t;
#define ff first
#define ss second
#define pb push_back
#define vmp make_pair
#define ppb pop_back
#define sorta(a,n) sort(arr,arr+n)
#define sortv(x) sort(x.begin(),x.end())

void file(){
    #ifdef LOCAL
    freopen("demo.in","r",stdin);
    freopen("demo.out","w",stdout);
    #endif
}

void test_case(){
    int n,m;
    cin>>n>>m;
    test(min(n%m,m-n%m));
}

int main(){
    fastio;
    file();
    // int T;
    // cin>>T;
    // for(int nr=1;nr<=T;++nr) {
    //     cout<<"Case #"<<nr<<": ";
		test_case();
    // }
}