#include<bits/stdc++.h>
using namespace std;
int n;
long long a[10001];
long long ans;
void dfs(int aa,int gs,int zgs,int sum)
{
    if(ans<sum)ans=sum;
    for(int i=aa+1;i<=n;i++)
    {
        if(gs<zgs&&sum^a[i]>sum)
        {
            dfs(i,gs+1,zgs,sum^a[i]);
        }
    }
}
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];
        if(a[i]>ans)ans=a[i];
    }
    for(int i=2;i<=n;i++)
    {
        dfs(0,0,i,0);
    }
    cout<<ans<<endl;
    return 0;
}