#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;
long long che=1,ans,a[10050],b[10050];
int n,k,t;
bool vis[10050];
inline void search(){
	if(k==t+1){
		che=b[1];
//		for(int  i=1;i<=t;i++)cout<<b[i];
//		cout<<endl;
		for(int i=2;i<=t;i++)che=che xor b[i];
		ans=max(che,ans);
		return;
	}
	for(int j=k;j<=n;j++){
		if(!vis[j]){
			b[k]=a[j];
			k++;
			vis[j]=1;
			search();
			k--;b[k]=0;vis[j]=0;
		}
	}
}
int main(){
	freopen("xor_equ.in","r",stdin);
	freopen("xor_equ.out","w",stdout);
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=2;i<=n;i++){
		k=t=i;k=1;
		search();
		}
	cout<<ans;
}