Delegate- ошибка компиляции - C#

 delegate int Rub(int i,int j);
    
    class Program
    {
         public static int Rub1(int x,int y)
        {
            if (x > 0 && y > 0)
                return 1;
            if (x < 0 && y > 0)
                return 2;
            if (x < 0 && y < 0)
                return 3;
            if (x > 0 && y < 0)
                return 4;
            return 0;
 
        }
        static void Main(string[] args)
        {
            Rub rb = new Rub(Rub1);
            int result = rb(3, -2);
           
            rb = new Rub(Rub1);
 
            switch (result)
            {
                case 3:
                    Console.WriteLine("Noqte birinci rubde yerleshir.");
                    break;
                case 2:
                    Console.WriteLine("Noqte ikinci rubde yerleshir.");
                    break;
                case 1:
                    Console.WriteLine("Noqte uchuncu rubde yerleshir.");
                    break;
                case 0:
                    Console.WriteLine("Noqte dorduncu rubde yerleshir.");
                    break;
 
            }
            
        }
    }
}