#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;


int main(){
	long long n;
	cin >> n;
	vector<long long> a(n);

	for(int i=0; i<n; i++){
		cin >> a[i];
	}
	
	int x = 0;
	for(long long i=32; i>=0; i--){
		long long y = 0;
		long long z = 0;

		long long mask_small = (1LL<<i)-1;
		long long mask_big = ~mask_small;
		
		for(int j=0; j<n; j++){
			y = max(y, ( (a[j]&mask_big)^x^(1LL<<i) ) | ((a[j]&mask_small)) );
			z = max(z, ( (a[j]&mask_big)^x^(0LL<<i) ) | ((a[j]&mask_small)) );
		}
		//cerr << y << " " << z << endl;
		if(y<=z){
			x |= 1<<i;
		}
	}

	long long ans = 0;
	for(int j=0; j<n; j++){
		ans = max(ans, a[j]^x);
		
	}

	cout << ans << endl;
	
	return 0;
}