#include <bits/stdc++.h>
using namespace std;

int n;
int a[100000];

int main()
{
	cin >> n;
	for (int i = 0; i < n; i++){
		cin >> a[i];
	}
	
	int cur = 0;
	for (int i = 30; i >= 0; i--){
		int nxt = cur | (1 << i);
		int mx = 0, my = 0;
		for (int j = 0; j < n; j++){
			mx = max(mx, a[j] ^ cur);
			my = max(my, a[j] ^ nxt);
		}
		if (mx > my) cur = nxt;
	}
	
	int res = 0;
	for (int i = 0; i < n; i++){
		res = max(res, cur ^ a[i]);
	}
	
	cout << res << endl;
}