#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	int x, y;
	cin>>x>>y;
	if(x==y) cout<<0<<endl;
	else if(y==0) cout<<1<<endl;
	else if(x==0) cout<<2<<endl;
	else if(x+y==0) cout<<3<<endl;
	else cout<<-1<<endl;
	return 0;
}