#include <bits/stdc++.h>  //�ص������㰮�ҵĶ���
using namespace std;
#define endl '\n'
#define ll long long
#define ld long double
#define umap unordered_map
#define rep(i, l, r) for (int i = l; i <= r; i++)
#define rep_(i, l, r) for (int i = l; i >= r; i--)
#define debug(a) cout << #a << "=" << a << endl;
#define pb push_back
#define all(v) v.begin(), v.end()
#define alls(a) a + 1, a + 1 + n
#define cy cout << "YES" << endl
#define cn cout << "NO" << endl
#define c1 cout << -1 << endl
int _, n, k, m;
typedef pair<int, int> PII;
priority_queue<int> maxx;
priority_queue<int, vector<int>, greater<int> > minx;
const int N = 2e5 + 10, inf = 1e9;
const double eps = 1e-8;
const double pi = acos(-1);
const int mod = 1e9 + 7;

void solve() {
  cin >> n;
  vector<int> a(n);
  map<int, int> mp;
  for (int i = 0; i < n; i++) cin >> a[i], mp[a[i]]++;

  int ma1 = -1, ma2 = -1;
  int t1, t2;
  for (auto &[x, y] : mp) {
    if (y > ma1) {
      ma1 = y;
      t1 = x;
    }
  }
  for (auto &[x, y] : mp) {
    if (y > ma2 && y < ma1) {
      ma2 = y;
      t2 = x;
    }
  }
  if(ma1 >= 3) ma2 = ma1 - 2;
  //cout << ma2 << endl;
  int t = ma1 | ma2;
  cout << t << endl;
}

int main() {
  /*ios::sync_with_stdio(false);
  cin.tie(nullptr);*/
  cin >> _;
  //_ = 1;
  while (_--) {
    solve();
  }
  return 0;
}