//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <queue>

using namespace std;

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);
const int INF = 1234567890;

VI a;
int solve(int d, VI num, int bit){
  if(SZ(num) == 1)
	return (a[num[0]] & ~((1<<(d+1))-1))^bit;

  VI t[2];
  REP(i,SZ(num))
	t[a[num[i]]>>d&1].PB(num[i]);

  if(d == 0)
	return (SZ(t[0]) == 0 || SZ(t[1]) == 0)?
	  ((a[num[0]]^bit) & ~1): ((a[num[0]]^bit) | 1);
  
  if(SZ(t[0]) == 0)
	return solve(d-1, t[1], bit|(1<<d));
  if(SZ(t[1]) == 0)
	return solve(d-1, t[0], bit);

  return min(solve(d-1, t[0], bit|(1<<d)), solve(d-1, t[1], bit));
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N; cin >> N;
  a.assign(N,0);
  REP(i,N) cin >> a[i];

  VI t;
  REP(i,N) t.PB(i);
  cout << solve(30, t, 0) << endl;
  
  return 0;
}