#include <iostream>
#include <vector>
using namespace std;
int dfs(vector<int> &A, vector<bool> &used, int X){
	int N = A.size();
	vector<int> r;
	for (int i = 0; i < N; i++){
		if (!used[i]){
			r.push_back(i);
		}
	}
	if (r.empty()){
		return X;
	} else {
		int cnt = r.size();
		int ans = 0;
		used[r[0]] = true;
		for (int i = 1; i < cnt; i++){
			used[r[i]] = true;
			ans = max(ans, dfs(A, used, X ^ (A[r[0]] + A[r[i]])));
			used[r[i]] = false;
		}
		used[r[0]] = false;
		return ans;
	}
}
int main(){
	int N;
	cin >> N;
	vector<int> A(N);
	for (int i = 0; i < N; i++){
		cin >> A[i];
	}
	vector<bool> used(N, false);
	cout << dfs(A, used, 0) << endl;
}