#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>

//#include<bits/stdc++.h>


using namespace std;



int main() {
	
	int a, b;
	cin >> a >> b;
	if (a == b) {
		cout << 0 << endl;
		return 0;
	}
	

	if (!b)cout << 1 << endl;
	else if (!a)cout << 2 << endl;
	else if (abs(a) == abs(b))cout << 3 << endl;
	else cout << -1 << endl;

	return 0;


		
}