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>
#define REP(i, n) for (int i = 1; i <= n; i++)
#define rep(i, n) for (int i = 0; i < n; i++)
#define ll long long
using namespace std;

ll K;

ll aaa(int a){
    ll b  = a % K;
    ll c  =abs(b - K);
    return min(b,c);
}

ll bbb(int a){
    ll b = abs(a-K);
    if(b > a){
        return abs(b - K);
    }
    return min(b,bbb(b));
}

int main()
{
    ll N;
    ll ans;
    ll keep;
    cin >> N >> K;
    
    ans = min(aaa(N),bbb(N));
    ans = min(ans , N);
    cout << ans << endl;
}