Multiplication Sign

using System;

class MultiplicationSign
{
    static void Main()
    {
        Console.Write("Write three numbers: ");
        double a = double.Parse(Console.ReadLine());
        double b = double.Parse(Console.ReadLine());
        double c = double.Parse(Console.ReadLine());

        if ((a*b*c)>0)
        {
            Console.WriteLine("+");
        }
        else if (a==0 || b==0 || c==0)
        {
            Console.WriteLine("0");
        }
        else
        {
            Console.WriteLine("-");
        }
    }
}