PeriodicTable

namespace PeriodicTable
{
    using System;
    using System.Collections.Generic;

    public class PeriodicTable
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            SortedSet<string> chemicalsSet = new SortedSet<string>();

            for (int i = 0; i < n; i++)
            {
                string[] chemicals = Console.ReadLine().Split(' ');

                foreach (var item in chemicals)
                {
                    chemicalsSet.Add(item);
                }
            }


            foreach (var item in chemicalsSet)
            {
                Console.Write(item + " ");
            }
        }
    }
}