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>
    #define ll long long
    #define rep(i,a,b) for(i=a;i<b;i++)
    #define pb push_back
    #define all(v) v.begin(),v.end()
    #define F first
    #define S second
    #define vi vector < ll  int >
    #define CLR(a) memset((a),0,sizeof(a))
    #define mp make_pair
    #define hell 1000000007
    using namespace std;
    ll mod=998244353;
ll pr( ll x , ll y)
{
    ll ans=1;
    if(y==0) return ans;
    while(y>1)
    {
        if(y&1) ans*=x;
        x*=x;
        y/=2;
        x%=mod;
        ans%=mod;
    }
    ans*=x;
    ans%=mod;
    return ans;
}
ll fact( ll n)
{
    ll ans=1,i;
    rep(i,1,n+1)
    {
        ans*=i;
        ans%=mod;
    }
    return ans;
}
ll in(ll x) { return  pr(x,mod-2);}

void solve()
{
 ll i,j=1,k,n,m=0,f,s1=0,x,c=1,y=0,a=0,b=0,d;
 cin>>n>>m;
 if(n%m==0) {cout<<0; return;}
 if(n>m)
 {
     n=n-(n/m)*m;
 }
 if(abs(n-m)<n) cout<<abs(n-m);
 else cout<<n;
}


 //}

    signed main()
    {
        ios::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);
        int t=1;
        // cin>>t;
        while(t--)
        solve();
    }