#include <bits/stdc++.h>
using namespace std;

using i64 = long long;

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    auto solve = [&]() {
        i64 a, b;
        cin >> a >> b;

        i64 r = a % b;
        if (r < 0) {
            r += abs(b);
        }

        cout << r << '\n';
    };
    
    solve();
    
    return 0;
}