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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int A,B; cin >> A >> B; 
    if(B < 0) A *= -1,B *= -1;
    A %= B;
    A += B;
    A %= B;
    cout << A << endl;
}