using System;

using System.Threading;

​

namespace Program

{

    public class Program

    {

        public static void Main(string[] args)

        {

        }

    }

}

​

class A {

    class ClassInAClass{

    }

}

​

interface B{

    class ClassInAnInterface {

    }

}

​

class C{

    interface InterfaceInAClass {

    }

}

​

interface D{

    interface InterfaceInAnInterface {

    }

}