#include <bits/stdc++.h>
using namespace std;

int n, a[1000005], t[10000005][2], p = 1, ans;

void insert(int u, int x, int b) {
    if (!x) return;
    int j = (x >> b) & 1;
    if (!t[u][j]) t[u][j] = ++p;
    insert(t[u][j], x - (j << b), b - 1);
}

int search(int u, int x) {
    int res = 0;
    for (int i = 30; i >= 0; i--) {
        if (!u) break;
        int j = (x >> i) & 1;
        t[u][!j] ? res += 1 << i, u = t[u][!j] : u = t[u][j];
    }
    return res;
}

int main() {
    cin >> n;
    for (int i = 0; i < n; i++) scanf("%d", &a[i]), insert(1, a[i], 30);
    for (int i = 0; i < n; i++) ans = max(ans, search(1, a[i]));
    cout << ans;
    return 0;
}