#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <cstring>
#include <cctype>
#include <set>
#include <map>
using namespace std;
#define MAXN (10005)

//#define dbg

void set_file()
{
	freopen("xor_equ.in", "r", stdin);
	freopen("xor_equ.out", "w", stdout);
}

long long num[MAXN];
long long dp[MAXN];

int main()
{
#ifndef dbg
	set_file();
#endif
	int i,j,k;
	int n;
	scanf("%d", &n);
	for(i = 1; i <= n; i++)
		scanf("%d", num+i);
	long long s = 0;
	dp[1] = num[1];
	for(i = 1; i <= n+1; i++)
	{
		
		for(j = 1; j < i; j++)
		{
			dp[i] = max(dp[i], dp[j] ^ num[j+1]);
			s = max(s, dp[i]);
		}
		
	}
	cout << s << endl;
	return 0;
}