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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
const int MAX = 110;
int main() {
    long long x, y;
    scanf("%lld %lld", &x, &y);
    long long ans = x;
    set<long long>vstd;
    if(x%y == 0){
        puts("0");
        exit(0);
    } else if(y%x == 0){
        printf("%lld\n", x);
        exit(0);
    }
    if(x > y) {
        long long lower = (ceil(x/y) - 1ll) * y;
        x -= lower;
    }
    do {
        vstd.insert(x);
        ans = min(ans, x);
        x = abs(x - y);
    }while(!vstd.count(x));
    printf("%lld\n", ans);
    return 0;
}