#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
ll a,b;

void solve(){
    int c = a%b;
    if(c < 0) c += abs(b);
    cout<<c<<endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> a >> b;
    solve();
}