#include<algorithm>
#include<cstring>
#include<string>
#include<cassert>
#include<cmath>
#include<climits>
#include<iomanip>
#include<stack>
#include<unordered_map>
#include<bitset>
#include<limits>
#include<complex>
#include<array>
#include <iostream>

using namespace std;
#define rep(i,m,n) for(int (i)=(int)(m);i<(int)(n);i++)
#define REP(i,n) rep(i,0,n)
#define ll long long
#define ull unsigned long 

#define ull unsigned long long
int main()
{
  ll ans;
  ll a,b;
  cin >> a >> b;
  if(b == 0){ ans=1;}
  else if(a == -1){ans=2;}
  else ans =-1;
    
    cout << ans << endl;
}