#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <numeric>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <functional>
#include <iomanip>
using namespace std;
using ll = long long;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n_):i({0}),n({n_}){}range(int i_,int n_):i({i_}),n({n_}){}I& begin(){return i;}I& end(){return n;}};


template<class T, class U> ostream& operator<<(ostream& os, const pair<T, U>& p){ return os << "{" << p.first << ", " << p.second << "}"; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> ostream& operator<<(ostream& os, const set<T>& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }

#ifdef ONLINE_JUDGE
#define dump(expr) ;
#else
#define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; }
#endif

struct T {
  T *zero, *one;
  T() : zero(nullptr), one(nullptr) {};
};

const int N = 31;

ll dp(T* now, int h) {
  if (now == nullptr) return 0;
  if (now->zero && now->one) {
    dump(now << " " << h);
    return (1LL << h) + min(dp(now->zero, h - 1), dp(now->one, h - 1));
  }
  return dp(now->zero, h - 1) | dp(now->one, h - 1);
}

ll solve() {
  int n; cin >> n;
  T* par = new T();
  while (n--) {
    ll x; cin >> x;
    T* now = par;
    for (int i : range(N)) {
      if (x & (1LL << (N - 1 - i))) {
        if (now->one == nullptr) now->one = new T();
        now = now->one;
      } else {
        if (now->zero == nullptr) now->zero = new T();
        now = now->zero;
      }
    }
  }
  ll res = dp(par, N - 1);
  return res;
}

int main() {
  cout << fixed << setprecision(12);
  cout << solve() << endl;
}