using System;

public class Hello
{
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = int.Parse(line[0]);
        var b = int.Parse(line[1]);
        Console.WriteLine(getAns(a,b));
    }
    public static int getAns (int a, int b)
    {
        if (a == b) return 0;
        if (a + b == 0) return 3;
        if (a == 0 && b != 0) return 2;
        if (a != 0 && b == 0) return 1;
        return -1;
    }
}