#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<cmath>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<numeric>
#include<functional>
#include<complex>

using namespace std;
#define BET(a,b,c) ((a)<=(b)&&(b)<(c))
#define FOR(i,n) for(int i=0,i##_end=(int(n));i<i##_end;i++)
#define SZ(x) (int)(x.size())
#define ALL(x) (x).begin(),(x).end()
#define MP make_pair
#define FOR_EACH(it,v) for(__typeof(v.begin()) it=v.begin(),it_end=v.end() ; it != it_end ; it++)
typedef vector<int> VI;
typedef vector<VI> VVI;

int dfs(const VI& A, int begin, int end, int bit){
    if(begin == end) return 0 ;
    if(bit < 0) return 0;
    int start0 = begin;
    int start1 = end;
    for(int i=begin;i<end;i++){
        if((1<<bit) & A[i]) {
            start1 = i;
            break;
        }
    }
    int num0 = start1 - start0;
    int num1 = end - start1;
    int val = 1<<30;
    if(num0 && num1){
        val = min(val, dfs(A, start0, start1, bit-1) | (1<<bit));
        val = min(val, dfs(A, start1, end, bit-1) | (1<<bit));
    }else if(num0) {
        val = min(val, dfs(A, start0, start1, bit-1));
    }else {
        val = min(val, dfs(A, start1, end, bit-1));
    }

    return val;
}

int main()
{
    int N;
    cin>>N;
    VI A(N);
    FOR(i,N) cin>>A[i];
    sort(ALL(A));
    cout<<dfs(A,0,N,30)<<endl;
    return 0;
}