#include <bits/stdc++.h>
using namespace std;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FORR(x,arr) for(auto&& x:arr)
#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define RFOR(i,a,b) for (int i = (b)-1; i >= (a); i--)
#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(x) (x).begin(), (x).end()
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define RITR(x,c) for(__typeof(c.rbegin()) x=c.rbegin();x!=c.rend();x++)
#define BIT(n) (1LL<<(n))
#define SZ(x) ((int)(x).size())
typedef long long ll;
// -------------------------------------

int dfs(int b, vector<int>& a) {
  if (SZ(a) <= 1) return 0;
  vector<int> a1, a2;
  int bb = BIT(b);
  FORR(x, a) {
    if (x & bb) a1.push_back(x);
    else a2.push_back(x);
  }

  if (b == 0) {
    if (SZ(a1) == 0 || SZ(a2) == 0) return 0;
    else return 1;
  }
  else {
    if (SZ(a1) == 0 || SZ(a2) == 0) return dfs(b-1, a);
    return bb + min(dfs(b-1, a1), dfs(b-1, a2));
  }
}

int main() {
  int n;
  cin >> n;
  vector<int> a(n, 0);;
  REP(i, n) {
    cin >> a[i];
  }

  int ans = dfs(30, a);
  cout << ans << endl;

  return 0;
}