#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout <<#x<<" = "<<(x)<<endl
#define spair(p) cout <<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout <<" "<<kbrni;cout<<endl

using namespace std;

typedef pair<int,int>P;

int dfs(int keta,vector<int>& vec)
{
    if(vec.size() <= 1){
        return 0;
    }
    vector<int> u,v;
    rep(i,vec.size()){
        if((vec[i] >> keta) & 1){
            v.pb(vec[i]^(1 << keta));
        }else{
            u.pb(vec[i]);
        }
    }
    if(u.size() == 0){
        return dfs(keta-1,v);
    }else if(v.size() == 0){
        return dfs(keta-1,u);
    }else{
        return (1 << keta) + min(dfs(keta-1,u),dfs(keta-1,v));
    }
}

int main()
{
    int n;
    cin >> n;
    vector<int> vec(n);
    rep(i,n){
        cin >> vec[i];
    }
    sort(all(vec));
    vec.erase(unique(all(vec)),vec.end());
    cout << dfs(29,vec) << endl;
    return 0;
}