#include <algorithm> #include <cstring> #include <deque> #include <iostream> #include <limits> #include <map> #include <queue> #include <set> #include <stack> #include <string> #include <vector> #define rep(i, a, n) for(int i = a; i < n; i++) using namespace std; using ll = long long; using P = pair<int, int>; int main() { int a, b; cin >> a >> b; if(b == 0){ cout << 1 << endl; return 0; } if(a == -1){ cout << 2 << endl; } else cout << -1 << endl; return 0; }