#include <cstdio>
#include <algorithm>
#include <stack>
#include <queue>
#include <deque>
#include <vector>
#include <string>
#include <string.h>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <map>
#include <set>
#include <iostream>
#include <sstream>
#include <numeric>
#include <cctype>
#include <bitset>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define gep(i,g,j) for(int i = g.head[j]; i != -1; i = g.e[i].next)
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcount
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define df(x) int x = in()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
inline int in() { int x; scanf("%d",&x); return x;}
inline void priv(vi a) { rep(i,sz(a)) printf("%d%c",a[i],i==sz(a)-1?'\n':' ');}

const int MX = 100005, INF = 1001001001;
const ll LINF = 1e18;
const double eps = 1e-10;

int dfs(vi a, int x) {
  if (x == 0 || sz(a) == 0) return 0;
  vvi b(2);
  rep(i,sz(a)) {
    if (a[i] >= x) b[1].pb(a[i]^x);
    else b[0].pb(a[i]);
  }
  int ans;
  if (sz(b[0]) && sz(b[1])) ans = x + min(dfs(b[0],x>>1), dfs(b[1],x>>1));
  else ans = max(dfs(b[0],x>>1), dfs(b[1],x>>1));
  return ans;
}

int main() {
  int n;
  vi a;
  cin >> n;
  rep(i,n) a.pb(in());
  int ans = dfs(a, 1<<29);
  cout<<ans<<endl;
  return 0;
}