#include <iostream>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <vector>
#include <numeric>
#include <algorithm>
#include <queue>
#include <string>
#include <random>
#include <array>
#include <climits>
#include <map>
#include <cassert>
#include <stack>
#include <iomanip>
#include <cfloat>
#include <bitset>
#include <fstream>
#include <chrono>



int main() {
	constexpr int MAX_V = 4000000;
	int n; std::cin >> n;
	std::vector<int> num(n);
	for (auto& a : num) {
		std::cin >> a;
	}
	std::bitset<MAX_V + 1> bit; bit.set(0);
	for (const auto a : num) {
		bit ^= bit << a;
	}
	int result = 0;
	for (auto i = 1; i <= MAX_V; ++i) {
		if (bit.test(i)) {
			result ^= i;
		}
	}
	std::cout << result << '\n';
}