Odd Number

using System;
using System.Collections.Generic;

class OddNumbers
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        Dictionary<long, int> allNumbers =
        new Dictionary<long, int>();
        for (int i = 0; i < n; i++)
        {
            long input = long.Parse(Console.ReadLine());
            if (allNumbers.ContainsKey(input))
            {
                allNumbers[input]++;
            }
            else
            {
                allNumbers.Add(input, 1);
            }
        }
        foreach (var item in allNumbers)
        {
            if (item.Value % 2 != 0)
            {
                Console.WriteLine(item.Key);
            }
        }
    }
}