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<bits/stdc++.h>
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<map>
#include<queue>
#include<stack>
#include<set>
//#include<unordered_map>
using namespace std;
#define int long long
#define ll long long
#define str string
#define db double
#define ac() cout<<"Yes"<<endl
#define wa()  cout<<"No"<<endl
#define ddd cout<<"---debug---"<<endl;
#define ff(a,b) for(signed long long (a)=1;(a)<=(b);(a)++)
#define fff(a,b) for(signed long long (a)=0;(a)<(b);(a)++)
#define re readdd()
#define pr(a) printtt(a)
#define pee puts("");
#define eee putchar(' ');
#define pss(a) push_back(a)
#define ps(a) push(a)
int gcd(int a,int b){return b==0?a:gcd(b,a%b);}//
int ppow(int a,int b,int mod){a%=mod;//
int ans=1%mod;while(b){if(b&1)ans=(long long)ans*a%mod;
a=(long long)a*a%mod;b>>=1;}return ans;}
int readdd(){int x=0,f=1;char c=getchar();//
while(!isdigit(c)&&c!='-')c=getchar();
if(c=='-')f=-1,c=getchar();
while(isdigit(c))x=x*10+c-'0',c=getchar();
return f*x;}
void printtt(int x){if(x<0)putchar('-'),x=-x;
if(x>=10)printtt(x/10);putchar(x%10+'0');}
bool addd(int a,int b){return a>b;};
//
const int maxm=2e5+5;
map<int,int>mark;
signed main(){
    int x=re,k=re;
    int ans=x;
    int t=x/k;
    ans=min(ans,x-t*k);
    ans=min(ans,abs(x-(t+1)*k));
    pr(ans);pee;
    return 0;
}