using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine(typeof(void));

        Console.WriteLine(Console.WriteLine("abc"));

    }

}

​

public static class StaticClass

{

    public class InstanceClass

    {

        internal int oldValue;

        public int Value;

    }

​

    public static void Backup(InstanceClass ic)

    {

        ic.oldValue = ic.Value;

    }

​

    public static void Restore(InstanceClass ic)

    {

        ic.Value = ic.oldValue;

    }

}