#include<bits/stdc++.h>
using namespace std;
#define inf INT_MAX
#define INF LLONG_MAX
#define ll long long
#define ull unsigned long long
#define M (int)(1e9+7)
#define P pair<int,int>
#define FOR(i,m,n) for(int i=(int)m;i<(int)n;i++)
#define RFOR(i,m,n) for(int i=(int)m;i>=(int)n;i--)
#define rep(i,n) FOR(i,0,n)
#define rrep(i,n) RFOR(i,n,0)
#define all(a) a.begin(),a.end()
const int vx[4] = {0,1,0,-1};
const int vy[4] = {1,0,-1,0};
#define F first
#define S second
#define PB push_back
#define EB emplace_back
#define int ll
#define vi vector<int>
#define IP pair<int,P>
#define PI pair<P,int>
#define PP pair<P,P>
#define Yes(f){cout<<(f?"Yes":"No")<<endl;}
#define YES(f){cout<<(f?"YES":"NO")<<endl;}
#define MPlus(x,y) {x=(x+y)%M;}
#define MSub(x,y) {x=(x-y+M)%M;}
#define MMul(x,y) {x=(x*y)%M;}


vector<vector<P>> allPair(vi v){
  vector<vector<P>> ret;  
  do{
    vector<P> res;
    rep(i,v.size()/2){
      res.PB(P(v[i],v[i+v.size()/2]));
    }
    ret.PB(res);
    reverse(v.begin()+v.size()/2,v.end());
  }while(next_permutation(all(v)));

  return ret;
}


signed main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout<<fixed<<setprecision(20);

  int n;
  cin>>n;
  vi a(n);
  rep(i,n){
    cin>>a[i];
  }

  vi it(n);
  rep(i,n){
    it[i]=i;
  }

  vector<vector<P>> itr=allPair(it);

  int ans=0;
  for(vector<P> it:itr){
    int s=0;
    rep(i,it.size()){
      s+=(a[it[i].F]^a[it[i].S]);
    }
    ans=max(s,ans);
  }

  cout<<ans<<endl;



}