using System;               

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var red = new Color() {ColorName = "Red"};      

        var green = new Color() {ColorName = "Green"};

        var blue = new Color() {ColorName = "Blue"};

​

        var colors = new List<Color>(){

            red, green, blue

        };

        var favRed = new FavouriteColour() {

            Color = red

        };

        var favGreen = new FavouriteColour() {

            Color = green

        };

        var favBlue = new FavouriteColour() {

            Color = blue

        };      

        var testPerson1 = new Person() {

            FavouriteColours = new List<FavouriteColour>() {

                favRed, favGreen

            }

        };

        var testPerson2 = new Person() {

            FavouriteColours = new List<FavouriteColour>() {

                favRed, favBlue

            }

        };

        var people = new List<Person>() {

            testPerson1, testPerson2

        };

        var favoriteColours = people.SelectMany(p => p.FavouriteColours);

        foreach(var favoriteColour in favoriteColours) {    

            System.Console.WriteLine(favoriteColour.Color.ColorName);

        }

    }

    public class Person {

        public IList<FavouriteColour> FavouriteColours {get;set;}

    }

    public class FavouriteColour {

        public Color Color {get;set;}

    }

    public class Color {

        public string ColorName {get;set;}

    }

}