Odd Number

using System;

//You are given a list of N integer numbers all but one of which appears an even number of times.
//Write a program to find the one integer which appears an odd number of times.
//Input
//The input data is being read from the console.
//The number N is written on the first input line.
//On each of the following N lines there is one integer number written – the consequent number from the given list of numbers.
//The input data will always be valid and in the format described. There is no need to check it explicitly.
//Output
//The output data must be printed on the console.
//On the only output line you must print the integer from the list which appears an odd number of times.
//Constraints
//•   N will be positive odd integer number between 1 and 99 999, inclusive.
//•   All of the numbers in the list will be integer numbers between -9 223 372 036 854 775 808
//and 9 223 372 036 854 775 807, inclusive.


class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        long answer = 0;
        long num;
        for (int i = 0; i < n; i++)
        {
            num = long.Parse(Console.ReadLine());
            answer ^= num;
        }
        Console.WriteLine(answer);
    }
}