#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;


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