using System;
using System.Linq;

namespace Problem1047
{
    class Program
    {
        static void Main()
        {
            var value = GetLongArray();
            if(value[1] == 0)
            {
                Console.WriteLine(1);
            }
            else if(value[0] == -1)
            {
                Console.WriteLine(2);
            }
            else
            {
                Console.WriteLine(-1);
            }

        }
        public static int GetInt() => int.Parse(Console.ReadLine());
        public static int[] GetIntArray() => Console.ReadLine().Split().Select(int.Parse).ToArray();
        public static double GetDouble() => double.Parse(Console.ReadLine());
        public static double[] GetDoubleArray() => Console.ReadLine().Split().Select(double.Parse).ToArray();
        public static long GetLong() => long.Parse(Console.ReadLine());
        public static long[] GetLongArray() => Console.ReadLine().Split().Select(long.Parse).ToArray();

    }
}