#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (int i = (s); i < (int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (int i = (int)(s - 1); i >= (int)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
T chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
T chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") { cout << (f ? yes : no) << "\n"; }

void solve() {
    int n;
    cin >> n;
    vl a(n);
    rep(i, n) cin >> a[i];
    auto dfs = [&](auto self, const vl& a, int b) -> ll {
        if (b < 0) return 0LL;
        vl x, y;
        rep(i, a.size()) {
            if (a[i] & (1LL << b)) x.emplace_back(a[i]);
            else y.emplace_back(a[i]);
        }
        if (x.empty() || y.empty()) return self(self, a, b - 1);
        ll res = 1e18;
        chmin(res, self(self, x, b - 1) + (1LL << b));
        chmin(res, self(self, y, b - 1) + (1LL << b));
        return res;
    };
    ll ans = dfs(dfs, a, 32);
    cout << ans << "\n";
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // multi-testcase
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}