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++ (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<iostream>
using namespace std;
using ll = long long;
ll n,k;
int main(){
	//freopen("in.txt","r",stdin);
	cin>>n>>k;
	if(n==k){
		cout<<0<<endl;
	}
	if(n<k) n=k+(k-n);
	
	cout<<(k-n%k)%k<<endl;
	return 0;
}