#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

int N;
ll a[100000];

int main() {
	cin >> N;
	rep (i, N) cin >> a[i];
	ll lb = *max_element(a, a + N);

	ll x = 0;
	repr (i, 32) {
		ll maxv = 0;
		ll y = x | (1ll << i);
		rep (j, N) {
			maxv = max(maxv, a[j] ^ y);
		}
		if (maxv < lb) {
			lb = maxv;
			x = y;
		}
	}

	cout << lb << endl;

	return 0;
}