05. Multiplication Sign

using System;

namespace MultiplicationSign
{
    class Program
    {
        static void Main(string[] args)
        {
            double n1 = double.Parse(Console.ReadLine());
            double n2 = double.Parse(Console.ReadLine());
            double n3 = double.Parse(Console.ReadLine());

            Console.WriteLine(ProductValue(n1, n2, n3));
        }

        static string ProductValue(double n1, double n2, double n3)
        {
            string result = "positive";

            if (n1 == 0 || n2 == 0 || n3 == 0)
            {
                result = "zero";
            }
            else if (n1 < 0 || n2 < 0 || n3 < 0)
            {
                if (!(n1 < 0 && n2 < 0 && n3 > 0 || n1 < 0 && n3 < 0 && n2 > 0 || n2 < 0 && n3 < 0 && n1 > 0))
                {
                    result = "negative";
                }
            }

            return result;
        }
    }
}