internal class Renovation
{
    static int Id => Thread.CurrentThread.ManagedThreadId;
    static async Task BuyPaint()
    {
        Console.WriteLine($"{Id} Placing an order for paint at a local shop - it'll be delivered quickly.");
        await Task.Delay(TimeSpan.FromSeconds(2));
        Console.WriteLine($"{Id} Paint delivered!");
    }

    static async Task BuyWoodenFloor()
    {
        Console.WriteLine($"{Id} Placing an order for wooden floor. The delivery will take over a month.");
        await Task.Delay(TimeSpan.FromSeconds(20));
        Console.WriteLine($"{Id} Wooden floor is finally delivered!");
    }

    static async Task RemoveFurniture()
    {
        Console.WriteLine($"{Id} Starting to remove the furniture... This will take a few days.");
        await Task.Delay(TimeSpan.FromSeconds(5));
        Console.WriteLine($"{Id} Removed all furniture from the room!");
    }

    static async Task PaintingTheWalls()
    {
        Console.WriteLine($"{Id} Now let's paint the walls - should be fairly quick.");
        await Task.Delay(TimeSpan.FromSeconds(5));
        Console.WriteLine($"{Id} Walls are painted!");
    }

    static async Task InstallNewFloor()
    {
        Console.WriteLine($"{Id} Let's install the floor.");
        await Task.Delay(TimeSpan.FromSeconds(5));
        Console.WriteLine($"{Id} Floors are installed!");
    }

    static async Task Main(string[] args)
    {
        Console.WriteLine($"Is Background thread? {Thread.CurrentThread.IsBackground}");
        Console.WriteLine($"Is SynchronizationContext null? {System.Threading.SynchronizationContext.Current == null}");

        Task paint = BuyPaint();
        Task woodenFloor = BuyWoodenFloor();
        Console.WriteLine($"{Thread.CurrentThread.ManagedThreadId} Placed all orders! Let's remove all the furniture from the room...");
        await RemoveFurniture();

        await paint;
        await PaintingTheWalls();

        await woodenFloor;
        await InstallNewFloor();

        Console.WriteLine($"{Thread.CurrentThread.ManagedThreadId} The renovation is done :)");
        Console.WriteLine($"Is Background thread? {Thread.CurrentThread.IsBackground}");
    }
}

PS C:\Users\darya\VSCode> dotnet run
**Is Background thread?** False
Is SynchronizationContext null? True
1 Placing an order for paint at a local shop - it'll be delivered quickly.
1 Placing an order for wooden floor. The delivery will take over a month.
1 Placed all orders! Let's remove all the furniture from the room...
1 Starting to remove the furniture... This will take a few days.
5 Paint delivered!
5 Removed all furniture from the room!
5 Now let's paint the walls - should be fairly quick.
5 Walls are painted!
5 Wooden floor is finally delivered!
5 Let's install the floor.
5 Floors are installed!
5 The renovation is done :)
**Is Background thread?** True

public class Main {
    static int getId() {
        return (int) Thread.currentThread().threadId();
    }

    static void buyPaint() {
        try {
            System.out.println(getId() + " Placing an order for paint at a local shop - it'll be delivered quickly.");
            TimeUnit.SECONDS.sleep(2);
            System.out.println(getId() + " Paint delivered!");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    static void buyWoodenFloor() {
        try {
            System.out.println(getId() + " Placing an order for wooden floor. The delivery will take over a month.");
            TimeUnit.SECONDS.sleep(20);
            System.out.println(getId() + " Wooden floor is finally delivered!");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    static void removeFurniture() {
        try {
            System.out.println(getId() + " Starting to remove the furniture... This will take a few days.");
            TimeUnit.SECONDS.sleep(5);
            System.out.println(getId() + " Removed all furniture from the room!");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    static void paintingTheWalls() {
        try {
            System.out.println(getId() + " Now let's paint the walls - should be fairly quick.");
            TimeUnit.SECONDS.sleep(5);
            System.out.println(getId() + " Walls are painted!");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    static void installNewFloor() {
        try {
            System.out.println(getId() + " Let's install the floor.");
            TimeUnit.SECONDS.sleep(5);
            System.out.println(getId() + " Floors are installed!");
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {
        Executor executor = Executors.newFixedThreadPool(/* nThreads= */ 3);
        CompletableFuture<Void> paint = CompletableFuture.runAsync(Main::buyPaint, executor);
        CompletableFuture<Void> woodenFloor = CompletableFuture.runAsync(Main::buyWoodenFloor, executor);

        System.out.println(getId() + " Placed all orders! Let's remove all the furniture from the room...");

        removeFurniture();

        paint.join();
        CompletableFuture.runAsync(Main::paintingTheWalls, executor).join();

        woodenFloor.join();
        CompletableFuture.runAsync(Main::installNewFloor, executor).join();

        System.out.println(getId() + " The renovation is done :)");
    }
}

23 Placing an order for paint at a local shop - it'll be delivered quickly.
24 Placing an order for wooden floor. The delivery will take over a month.
1 Placed all orders! Let's remove all the furniture from the room...
1 Starting to remove the furniture... This will take a few days.
23 Paint delivered!
1 Removed all furniture from the room!
25 Now let's paint the walls - should be fairly quick.
25 Walls are painted!
24 Wooden floor is finally delivered!
23 Let's install the floor.
23 Floors are installed!
1 The renovation is done :)