#include <bits/stdc++.h>
#define CK(N, A, B) (A <= N && N < B)
#define REP(i, a, b) for (int i = a; i < b; i++)
#define RREP(i, a, b) for (int i = (b - 1); a <= i; i--)
#define p(s) cout<<(s)<<endl
#define F first
#define S second
typedef long long ll;

const int INF = 1e9;
const long long LLINF = 1e18;

using namespace std;

int dy[] = {0,1,0,-1};
int dx[] = {1,0,-1,0};
int dy8[] = {0,1,1,1,0,-1,-1,-1};
int dx8[] = {1,1,0,-1,-1,-1,0,1};

int N;
int A[20];
int ans;
int main(){
    cin>>N;
    REP(i, 0, N) cin>>A[i];

    sort(A, A+N);


    int b[N];
    REP(i,0,N){
        if(i <  N/2) b[i]=0;
        else b[i]=1;
    }
    do{
        vector<int> v1, v2;
        REP(i, 0, N){
            if(b[i]==1){
                v1.push_back(A[i]);
            }
            else{
                v2.push_back(A[i]);
            }
        }
        do{
            int tmp=0;
            REP(i, 0, N/2){
                tmp+=v1[i]^v2[i];
            }
            ans=max(ans, tmp);
        }while (next_permutation(v1.begin(), v1.end()));
    }while(next_permutation(b,b+N));

    cout<<ans<<endl;
    return 0;
}