#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b)*b; }
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T>& V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> >& Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T>& mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }
template<typename T>vector<T> make_v(size_t a){return vector<T>(a);}
template<typename T,typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type fill_v(T &t,const V &v){t=v;}
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type fill_v(T &t,const V &v){for(auto &e:t) fill_v(e,v);}
/*
 <url:>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */

template<class Type>
Type solve(Type res = Type()){
    ll n; cin >> n;
    vector<ll> a(n); for(auto& in:a) cin >> in;

    sort(a.begin(),a.end());

    res = *max_element(a.begin(), a.end());


    function<void(ll,ll,vector<ll>&)> dfs = [&](ll b,ll S,vector<ll>& a){
        vector<ll> L,R;
        if(b == -1){
            res = min(res,S);
            return;
        }

        for(int i = 0; i < (int)a.size(); i++){
            if((a[i]>>b)&1){
                L.push_back(a[i]-(1LL<<b));
            }else{
                R.push_back(a[i]);
            }
        }

        if(L.size() && R.empty()){
            dfs(b-1,S,L);
        }else if(L.empty() && R.size()){
            dfs(b-1,S,R);
        }else{
            // 1
            dfs(b-1,S+(1LL<<b),L);
            // 0
            dfs(b-1,S+(1LL<<b),R);
        }
    };
    dfs(31,0,a);

    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    // solve(0);
    cout << fixed << setprecision(15) << solve<ll>() << endl;
    return 0;
}