WhatIsTheDeclaration

namespace WhatIsTheDeclaration
{
    // 1st exercise
    public class Click {}
    public class Clack : Click {}

    // 2nd exercise
    public abstract class Top {}
    public class Tip : Top {}

    // 3rd exercise
    public abstract class Fee {}
    public abstract class Fi {}

    // 4th exercise
    interface Foo {}
    public class Bar : Foo {}
    public class Baz : Bar {}

    // 5th
    interface Zeta {}
    public class Alpha : Zeta {}
    interface Beta {}
    public class Delta : Alpha, Beta
}