#include <iostream>
#include <algorithm>
#include <vector>
#include <functional>

void solve() {
    int n;
    std::cin >> n;

    std::vector<int> xs(n);
    for (auto& x : xs) std::cin >> x;
    std::sort(xs.begin(), xs.end());

    std::function<int(int, int, int)> dfs =
        [&](int l, int r, int d) -> int {
        if (d < 0) return 0;

        int m = l;
        while (m < r && ((xs[m] >> d) & 1) == 0) ++m;

        if (m == l || m == r) {
            return dfs(l, r, d - 1);
        } else {
            return (1 << d) + std::min(dfs(l, m, d - 1), dfs(m, r, d - 1));
        }
    };

    std::cout << dfs(0, n, 30) << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}