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: Runtime Error)

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

int main(){
  long long n,k;
  cin>>n>>k;
  long long N=n;
  long long mn=100000000000000000000;
     while(n>=0){
        if(k==1){
            mn=0;
            break;
        }
        if(n%2==0 && k==2 ){
            mn=0;
            break;
        }
        mn=min(n,mn);
        if(n<k){
            n=k%n;
        }
        else{
            n=n%k;
        }
        if(n==mn){
        mn=min(n,mn);
            break;
        }
     }
     cout<<mn;

   return 0;
       }