SortedUniqueUsernames

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

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

            for (int i = 0; i < n; i++)
            {
                names.Add(username);
                username = Console.ReadLine();
            }

            foreach (string name in names)
            {
                Console.WriteLine(name);
            }
        }
    }
}