#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef pair<ll, ll> PP;
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx")
#define overload4(_1, _2, _3, _4, name, ...) name
#define overload3(_1, _2, _3, name, ...) name
#define rep1(n) for (ll i = 0; i < n; ++i)
#define rep2(i, n) for (ll i = 0; i < n; ++i)
#define rep3(i, a, b) for (ll i = a; i < b; ++i)
#define rep4(i, a, b, c) for (ll i = a; i < b; i += c)
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(n) for (ll i = n; i--;)
#define rrep2(i, n) for (ll i = n; i--;)
#define rrep3(i, a, b) for (ll i = b; i-- > (a);)
#define rrep4(i, a, b, c)                                                      \
  for (ll i = (a) + ((b) - (a)-1) / (c) * (c); i >= (a); i -= c)
#define rrep(...)                                                              \
  overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define elif else if
ll beki(ll i) { return 1ll << i; }
#define skip(M)                                                                \
  if (M)                                                                       \
  continue
#define all(v) v.begin(), v.end()
#define allm(x, y, M) for (auto [(x), (y)] : (M))
#define alls(i, S) for (auto(&i) : (S))
#define pb push_back
#define fi first
#define se second
#define outno                                                                  \
  print("NO");                                                                 \
  return
const ll INF = (1LL << 61) - 1;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll MAX_N1 = 200010;
const ll MAX_N2 = 500010;
template <class X> void print(X x) { cout << x << endl; }
void print(vl x) {
  for (ll i : x) {
    cout << i << " ";
  }
  cout << endl;
}
void print(vector<PP> x) {
  for (PP i : x) {
    cout << i.first << " " << i.second << endl;
  }
  cout << endl;
}
template <class X> int lbound(vector<X> &Y, X a) {
  return lower_bound(all(Y), a) - Y.begin();
}
template <class X> int ubound(vector<X> &Y, X a) {
  return upper_bound(all(Y), a) - Y.begin();
}
template <class X> X lbound2(vector<X> &Y, X a, int mode = 0) {
  int x = lbound(Y, a) - mode;
  if (x < 0 || x >= Y.size())
    return INF;
  return Y[x];
}
template <class X> X ubound2(vector<X> &Y, X a, int mode = 0) {
  int x = ubound(Y, a) - mode;
  if (x < 0 || x >= Y.size())
    return INF;
  return Y[x];
}
template <class... T> void cl(T &... t) { (..., (t.clear())); }
template <class... T> void in(T &... t) { (..., (cin >> t)); }
template <class... T> void put(vl &V, int n, int mode = 0) {
  ll k;
  if (mode == 0)
    cl(V);
  rep(i, n) {
    cin >> k;
    V.pb(k);
  }
}
int max_index(vl &V) { return max_element(all(V)) - V.begin(); }
int min_index(vl &V) { return min_element(all(V)) - V.begin(); }
ll sum(vl &V) { return accumulate(all(V), 0ll); }
template <typename T> void UNIQUE(vector<T> &v) {
  sort(v.begin(), v.end());
  v.erase(unique(v.begin(), v.end()), v.end());
}
template <typename T> T ADD(T a, T b) {
  T res;
  return __builtin_add_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
}
template <typename T> T MUL(T a, T b) {
  T res;
  return __builtin_mul_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
};
template <typename T> T POW(T a, int n) {
  T res = 1;
  for (; n > 0; n >>= 1, a *= a)
    if (n & 1)
      res *= a;
  return res;
}
template <class X> bool ma(X &a, X b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class X> bool mi(X &a, X b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
void vset(vl &A, ll n, ll k) { A = vl(n, k); }
void so(vl &A) { sort(all(A)); }
ll age(ll x, ll y) { return (x + y - 1) / y; }
ll a, b, c, d, e, f, h, x, y, z, p, q, n, t, r, k, w, l, ans, m, u, v;
ll codeforces = 1;
string S, T, U;
vl A, B, C, D;
vector<vl> g[MAX_N2];
vector<PP> VP, VP2;
set<ll> s1, s2;
void solve() {
  in(n);
  ans = INF;
  rep(n) {
    in(x);
    ans = ans & (INF - x);
  }
  rep(i, INF) {
    if (beki(i) & ans) {
      print(beki(i));
      return;
    }
  }
}
int main() {
  cout << fixed << setprecision(15);
  cin.tie(0);
  ios::sync_with_stdio(false);
  // cin >> codeforces;
  while (codeforces--) {
    ans = 0;
    solve();
  }
}