#include <bits/stdc++.h>
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define REP(i,k,n) for(ll i=k;i<(ll)(n);i++)
#define fore(i,a) for(auto &i:a)
using namespace std;
using ll = long long; 

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;
}