PeriodicTable

namespace PeriodicTable
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;

    public class Startup
    {
        public static void Main()
        {
            SortedSet<string> chemicalElements = new SortedSet<string>();

            int countOfInputLines = int.Parse(Console.ReadLine());
            for (int currLine = 0; currLine < countOfInputLines; currLine++)
            {
                string[] inputLine = Console.ReadLine().Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);

                inputLine.ForEach(s => chemicalElements.Add(s));
            }

            Console.WriteLine(string.Join(" ", chemicalElements));
        }
    }

    public static class ExtensionMethod
    {
        public static void ForEach(this string[] array, Action<string> actionToExecute)
        {
            foreach (string item in array)
            {
                actionToExecute(item);
            }
        }
    }
}