Write a program how do we add two numbers without using + operator in C#

class Loop

    {

        public static int Add(int num1, int num2)

        {

            if (num2 == 0)

                return num1;

            return Add(num1 ^ num2, (num1 & num2) << 1);

        }

        static void Main()

        {

            Console.WriteLine(Add(12, 9));

            Console.ReadLine();

        }

    }

Output:

21