using System;

public class MyClass

    {

        public static int MyMethod (ref int a)

        {

            return a +=3;

        }

    }

​

​

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Console.WriteLine();

        int a = 1;

        Console.WriteLine("1. Vairable a = {0}", a);

        MyClass.MyMethod(ref a);

        Console.WriteLine("2. Vairable a = {0}", a);

        Console.WriteLine("3. Vairable a = {0}", MyClass.MyMethod(ref a));

    }

}