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>
using namespace std;
typedef long long LL;
int main(int argc, char* argv[])
{
	LL N,K;
	cin>>N>>K;
	LL X;
	if (N>=K){
		X=N%K;
		if (X>0){
			while (2*X>K){
				X-=K;
				if (X<0){
					X=-X;
				}
			}
		}
	}else{
		X=N%K;
		while (2*X>K){
			X-=K;
			if (X<0){
				X=-X;
			}
		} 
	}
	cout<<X<<endl;
	return 0;
}