#include<iostream>
#include<vector>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

int f(int d,int N,vector<int>&A){
    if(d<0)return 0;
    vector<int>B,C;
    rep(i,N){
        if(A[i]>>d&1){
            B.push_back(A[i]);
        }else{
            C.push_back(A[i]);
        }
    }
    if(B.empty())return f(d-1,(int)C.size(),C);
    else if(C.empty())return f(d-1,(int)B.size(),B);
    else return (1<<d)^min(f(d-1,(int)C.size(),C),f(d-1,(int)B.size(),B));
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin>>N;
    vector<int>A(N);
    rep(i,N)cin>>A[i];
    cout<<f(30,N,A)<<"\n";
}