#include "bits/stdc++.h"
#define REP(i,n,N) for(ll i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const int INF = 1e9;
const int MOD = 1e9+7;
const ll LLINF = 1e18;


ll A[15];
int main(){
    int N;
    cin>>N;
    REP(i,0,N){
        cin>>A[i];
    }
    sort(A,A+N);
    vector<ll> b(N,1);
    REP(i,0,N/2){
        b[i]=0;
    }

    ll ans=0;
    do{
        vector<ll> now,op;
        REP(i,0,N){
            if(b[i]){
                now.push_back(A[i]);
            }else{
                op.push_back(A[i]);
            }
        }
        do{
            ll tmp=0;
            REP(i,0,N/2){
                tmp^=now[i]+op[i];
            }
            ans=max(ans, tmp);

        }while(next_permutation(ALL(now)));

    }while(next_permutation(ALL(b)));
    p(ans);
    return 0;
}