#include<bits/stdc++.h>
#define rep(i,a,b) for(ll i=ll(a);i<ll(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int N;
    cin >> N;
    vector<ll> A(N);
    ll maxi = 0;
    rep(i,0,N){
        cin >> A[i];
        maxi = max(maxi, A[i]);
    }
    for(ll i = 0;i < 32;i++){
        ll bit = (ll)1 << i;
        if(!(bit & maxi))continue;
        
        ll submax = 0;
        rep(j,0,N){
            submax = max(submax, A[j] ^ bit);
            //cout << (A[j] ^ bit) << " ";
        }
        //cout << endl;
        //cout << submax << " " << maxi << endl;
        if(submax >= maxi)continue;
        maxi = submax;
        rep(j,0,N){
            A[j] ^= bit;
        }
    }
    cout << maxi << endl;
    //cout << bitset<32>(maxi) << endl;
}