#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int func(vector<int>& a, int l, int r, int k)
{
    if (r-l<1) return 1<<30;
    if (k<0) return 0;
    int x=0, nr=r;
    for(int i=l+1; i<r; ++i) {
        if ((a[i]&(1<<k))!=(a[i-1]&(1<<k))) {
            x=(1<<k);
            nr=i;
            break;
        }
    }
    return x+min(func(a, l, nr, k-1), func(a, nr, r, k-1));
}

int main()
{
    cin.sync_with_stdio(0);
    cin.tie(0);

    int n; cin>>n;
    vector<int> a(n); for(auto& e: a) cin>>e;
    sort(begin(a), end(a));
    cout<<func(a, 0, n, 30)<<endl;
}