إضافة عنصر

using System;
using System.Collections.Generic;

class Program
{
    public static void AddElement(HashSet<string> set, string element)
    {
        // اكتب كودك هنا
    }
    
    public static void Main()
    {
        string[] initialElements = Console.ReadLine().Split(',');
        string elementToAdd = Console.ReadLine();
        
        HashSet<string> set = new HashSet<string>();
        foreach (string item in initialElements)
        {
            if (!string.IsNullOrWhiteSpace(item))
            {
                set.Add(item.Trim());
            }
        }
        
        AddElement(set, elementToAdd);
    }
}