#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int solve(vector<int>& v, int b) {
    if (b == -1) return 0;
    vector<int> v0, v1;
    for (int x : v) {
        if (x & (1 << b)) {
            x -= (1 << b);
            v1.push_back(x);
        } else {
            v0.push_back(x);
        }
    }
    if (v0.size() == v.size()) return solve(v0, b-1);
    else if (v1.size() == v.size()) return solve(v1, b-1);
    else return (1 << b) + min(solve(v0, b-1), solve(v1, b-1));
} 

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> v(n);
    for (int i = 0; i < n; i++) cin >> v[i];
    cout << solve(v, 29) << endl;
    return 0;
}