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 <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pdd;
typedef vector<ll> vll;
typedef vector<ld> vld;
typedef vector<pll> vpl;

#define ALL(a) a.begin(),a.end()
#define SZ(a) ((int)a.size())
#define FI first
#define SE second
#define REP(i,n) for(int i=0;i<((int)n);i++)
#define REP1(i,n) for(int i=1;i<((int)n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define PB push_back
#define EB emplace_back
#define MP(a,b) make_pair(a,b)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define yes cout<<"Yes"<<endl
#define YES cout<<"YES"<<endl
#define no cout<<"No"<<endl
#define NO cout<<"NO"<<endl
#define Decimal fixed<<setprecision(20)
#define INF 1000000000
#define LLINF 1000000000000000000LL

const int inf = 1e9;
const ll linf = 1LL << 50;
const double eps = 1e-10;
const int MOD = 1e9 + 7;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};

int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  ll n,k;
  cin>>n>>k;
  n%=k;

  ll ans=min(n,k-n);
  cout<<ans<<endl;
}