Composition Design Pattern

CompositionDesignPattern.cs

public abstract class Staff
{
    protected string Title;
        
    public Staff(string title)
    {
        this.Title = title;
    }

    public abstract void Add(Staff staff);
    public abstract void Remove(Staff staff);
    public abstract void ShowProfile(); 
}

public class LeafStaff
    :Staff
{
    public LeafStaff(string title)
        :base(title)
    {
    }

    public override void ShowProfile()
    {
        Console.WriteLine(" - Leaf : {0}", this.Title);
    }

    public override void Add(Staff staff)
    {
        Console.WriteLine("Cannot add to a LeafStaff");
    }

    public override void Remove(Staff staff)
    {
        Console.WriteLine("Cannot add to a LeafStaff");
    }
}

public class CompositionStaff
    :Staff
{
    private List<Staff> leafs = new List<Staff>(); 

    public CompositionStaff(string title)
        :base(title)
    {
    }

    public override void ShowProfile()
    {
        Console.WriteLine("+ Composition : {0}", this.Title);

        // Display each child element on this node
        foreach (Staff item in leafs)
        {
            item.ShowProfile();
        }
    }

    public override void Add(Staff staff)
    {
        leafs.Add(staff);
    }

    public override void Remove(Staff staff)
    {
        leafs.Remove(staff);
    }
}