#include <iostream>
using namespace std;

int main(void)
{
    int n;
    unsigned int a[100000];
    int b[32] = {0};
    unsigned int res = 0;
    cin >> n;
    for(int i = 0; i < n; i++) {
        cin >> a[i];
        res = max(res, a[i]);
    }
    unsigned int m = 0;
    for(int i = 31; i >= 0; i--) {
        unsigned int t = 0;
        unsigned int flag = 1 << i;
        m |= flag;
        for(int i = 0; i < n; i++)
            t = max(t, a[i] ^ m);
        if(t < res)
            res = t;
        else
            m ^= flag;
    }
    cout << res << endl;
    return 0;
}