Problem 4 - Odd Number

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OddNumber
{
    class OddNumber
    {
        static void Main(string[] args)
        {
            uint n = uint.Parse(Console.ReadLine());
            int counter = 1;

                List<long> list = new List<long>();
                for (int i = 0; i < n; i++)
                {
                    long num = long.Parse(Console.ReadLine());

                    list.Add(num);
                }
                for (int j = 0; j < n; j++)
                {
                    for (int i = 1; i < list.Count; i++)
                    {

                        if (list[0] == list[i])
                        {
                            counter++;
                        }

                    }
                    if(counter % 2 !=0 || counter == 1)
                    {

                        Console.WriteLine(list[0]);
                        break;
                    }
                    list.Remove(list[0]);
                    counter = 1;

                }
            }
        }
    }