#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;

int solve(int X,int Y) {
	if (X == Y)return 0;
	if (X == 0)return 2;
	else if (Y == 0)return 1;
	if (X + Y == 0)return 3;
	return -1;
}

int main()
{
	int X, Y; cin >> X >> Y;
	cout << solve(X, Y) << endl;
    return 0;
}