using System;
using System.Collections.Generic;
using System.Linq;

namespace EvenTimes
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            var dict = new Dictionary<int, int>();

            for (int i = 0; i < n; i++)
            {
                var input = int.Parse(Console.ReadLine());
                if (dict.ContainsKey(input))
                {
                    dict[input] +=1;
                }
                else
                {
                    dict.Add(input, 1);
                }

            }
            foreach (var item in dict)
            {
                if (item.Value % 2 ==0)
                {
                    Console.WriteLine(item.Key);
                }

            }
        }
    }
}