#include<iostream>
#include<algorithm>
using namespace std;
int n; int a[100000];
int solve(int i, int l, int r){
    int m=r+1;
    for(int j=l; j<=r; j++){
        if(((a[j]>>i)&1)==1){
            m=j;
            break;
        }
    }
    if(i==0){
        if(m==r+1 || m==l) return 0;
        else return 1;
    }
    if(m==r+1 || m==l) return solve(i-1, l, r);
    return (1<<i)+min(solve(i-1, l, m-1), solve(i-1, m, r));
}

int main(){
    cin>>n;
    for(int i=0; i<n; i++){
        cin>>a[i];
    }
    sort(a, a+n);
    cout<<solve(29, 0, n-1)<<endl;
    return 0;
}