#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long MOD = 1'000'000'007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;

ll N;
set<ll> S;
vector<ll> v;

int hoge(ll d, vector<ll>& v) {
	if (v.size() <= 1) return 0;
	int i, j;
	vector<ll> w[2];
	for (ll i = 0; i < v.size(); i++) {
		int x = v[i];
		w[(x >> d) & 1].push_back(x ^ (x&(1 << d)));
	}

	if (w[0].size() == 0) return hoge(d - 1, w[1]);
	if (w[1].size() == 0) return hoge(d - 1, w[0]);

	return (1 << d) + min(hoge(d - 1, w[0]), hoge(d - 1, w[1]));
}

void solve() {
	string s;
	cin >> N;
	ll x;
	for(ll i=0;i<N;i++) cin >> x, S.insert(x);
	for(auto p : S) v.push_back(p);

	cout << hoge(40, v) << endl;
}
int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/

	solve();
	return 0;
}