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

int main() {
    const int64_t m = 1000000000;
    int64_t a, b;
    cin >> a >> b;
    assert(-m <= a && a <= m);
    assert(-m <= b && b <= m);
    if (b == 0) {
        cout << 1 << endl;
    } else if (a == -1) {
        cout << 2 << endl;
    } else {
        cout << -1 << endl;
    }
}