//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
using ll = int64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T> >;
const int INF = 100010001;
const ll LINF = (ll)INF*INF*10;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

const int N = 1e5+10;

//head

int n;
vector<unsigned int> a;

unsigned int dfs(int i, vector<unsigned int> &u) {
  if(i == -1) return 0;
  unsigned int res = 0;
  vector<unsigned int> aur, ian;
  rep(k, u.size()) {
    if(u[k]>>i&1) aur.emplace_back(u[k]);
    else ian.emplace_back(u[k]);
  }
  if(aur.empty() or ian.empty()) {
    res = dfs(i-1, u);
  }
  else {
    res = min(dfs(i-1, ian), dfs(i-1, aur));
    res += 1<<i;
  }
  return res;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n;
  a.resize(n);
  rep(i, n) cin >> a[i];

  cout << dfs(31, a) << endl;
}