using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Four case test:");

        Test(FourCaseTest);

        Console.WriteLine();

        Console.WriteLine("Three case test:");

        Test(ThreeCaseTest);

        Console.WriteLine();

        Console.WriteLine("Two case test:");

        Test(TwoCaseTest);

        Console.WriteLine();

    }

    private static bool FourCaseTest(Span shift, Span person)

    {

        return person.Begin >= shift.Begin && person.Begin <= shift.End ||

                person.End >= shift.Begin && person.End <= shift.End ||

                person.Begin <= shift.Begin && person.End >= shift.End ||

                person.Begin >= shift.Begin && person.End <= shift.End;

    }

    private static bool ThreeCaseTest(Span shift, Span person)

    {

        return person.Begin >= shift.Begin && person.Begin <= shift.End ||

                person.End >= shift.Begin && person.End <= shift.End ||

                person.Begin <= shift.Begin && person.End >= shift.End;

    }

    private static bool TwoCaseTest(Span shift, Span person)

    {

        return person.Begin <= shift.End && person.End >= shift.Begin;

    }

    private static void Test(Func<Span, Span, bool> test)

    {

        // A shift is always 9am - 5pm

        var shift = new Span(new DateTime(2000, 1, 1, 9, 0, 0), new DateTime(2000, 1, 1, 17, 0, 0));

        bool result;

        // Case 1: Person works entirely before the shift - from 6am to 8am

        result = test(shift, new Span(new DateTime(2000, 1, 1, 6, 0, 0), new DateTime(2000, 1, 1, 8, 0, 0)));

        Console.WriteLine("Person works entirely before shift: " + result);

        // Case 2: Person starts work before the shift and ends during the shift - from 6am to 10am

        result = test(shift, new Span(new DateTime(2000, 1, 1, 6, 0, 0), new DateTime(2000, 1, 1, 10, 0, 0)));

        Console.WriteLine("Person starts work before shift and ends during shift: " + result);

        // Case 3: Person starts work before the shift and ends after the shift - from 6am to 6pm

        result = test(shift, new Span(new DateTime(2000, 1, 1, 6, 0, 0), new DateTime(2000, 1, 1, 18, 0, 0)));

        Console.WriteLine("Person starts work before shift and ends after shift: " + result);

        // Case 4: Person starts work after shift starts and ends before the shift ends - from 10am to 4pm

        result = test(shift, new Span(new DateTime(2000, 1, 1, 10, 0, 0), new DateTime(2000, 1, 1, 16, 0, 0)));

        Console.WriteLine("Person starts work after shift starts and ends before shift ends: " + result);

        // Case 5: Person starts work after shift starts and ends after the shift ends - from 10am to 6pm

        result = test(shift, new Span(new DateTime(2000, 1, 1, 10, 0, 0), new DateTime(2000, 1, 1, 18, 0, 0)));

        Console.WriteLine("Person starts work after shift starts and ends after shift: " + result);

        // Case 6: Person works entirely after the shift - from 6pm to 8pm

        result = test(shift, new Span(new DateTime(2000, 1, 1, 18, 0, 0), new DateTime(2000, 1, 1, 20, 0, 0)));

        Console.WriteLine("Person works entirely after shift: " + result);

    }

}

public class Span

{

    public DateTime Begin { get; }

    public DateTime End { get; }

    public Span(DateTime begin, DateTime end)

    {

        Begin = begin;

        End = end;

    }

}