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

int main(){
    int A, B;
    cin >> A >> B;
    if(B == 0){
        cout << 1 << endl;
    }else if(A == -1){
        cout << 2 << endl;
    }else{
        cout << -1 << endl;
    }
    return 0;
}