#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;

int main() {
	int n;

	cin >> n;
	vector<int> a(n, 0);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}

	int xx = 0;
	int max0, max1;
	for (int i = 20; i >= 0; i--) {
		 int x0 = xx;
		 int x1 = xx + (1 << i);
		 max0 = 0;
		 max1 = 0;
		for (int j = 0; j < n; j++) {
			max0 = max(max0, a[j] ^ x0);
			max1 = max(max1, a[j] ^ x1);
		}

		xx = max0 < max1 ? x0 : x1;
	}

	int ans = max0 < max1 ? max0 : max1;
	cout << ans << endl;
	return 0;
}