#include<bits/stdc++.h>
using namespace std;
#define ALL(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl; 
#define INF 1000000000
#define mod 1000000007
typedef long long ll;
const ll LINF = 1001002003004005006ll;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int n;
vector<ll> a;

ll f(int d,vector<int> ids){
    //d桁まで確定している
    if(ids.size()<=1) return 0;

    ll ret=0;
    vector<int> v0,v1;
    int i;
    for(i=d-1;i>=0;i--){
        int c0=0,c1=0;
        for(auto j:ids){
            if((a[j]>>i)&1) c1++;
            else            c0++;
        }
        if(c0==0 or c1==0) continue;
        ret+=(1<<i);
        for(auto j:ids){
            if((a[j]>>i)&1) v1.push_back(j);
            else            v0.push_back(j); 
        }
        break;
    }
    ret+=min(f(i,v1),f(i,v0));
    return ret;
}


signed main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    cin>>n;
    a.resize(n);
    rep(i,n) cin>>a[i];
    sort(ALL(a));

    vector<int> v(n);
    iota(ALL(v),0);
    cout<<f(31,v)<<endl;
    return 0;
}