#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 = 0; i < 32; i++) {
        int mf = -1;
        for(int j = 0; j < 32; j++) {
            unsigned int flag = (unsigned int)1 << j;
            if((m & flag) > 0)
                continue;
            m |= flag;
            unsigned int t = 0;
            for(int j = 0; j < n; j++)
                t = max(t, a[j] ^ m);
            if(t < res) {
                res = t;
                mf = j;
            }
            m ^= flag;
        }
        if(mf == -1)
            break;
        m |= 1 << mf;
    }
    cout << res << endl;
    return 0;
}