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;

#define sp(x) cout<<setprecision(x);
#define all(a) (a).begin(), (a).end()
#define inf 10000000
#define linf INT64_MAX*0.99
#define lint long long
#define FOR(i,a,b) for(lint i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define yes "Yes"
#define no "No"
#define divs 1000000007
#define dive 1000000009

typedef pair<int, int> P;

lint ctoi(char c) {
	if (c >= '0' && c <= '9') {
		return c - '0';
	}
	return 0;
}

lint euclidean_gcd(lint a, lint b) {
  lint r;
  while ((r=a%b)) {
    a = b;
    b = r;
  }
  return b;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
	lint n, k; cin>>n>>k;
	cout<<min(n%k,k-(n%k))<<endl;
    return 0;
}