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

#define ll long long
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define el '\n'
#define sz(a) (int)(a).size()
#define pi acos(-1)
// #define int ll

#ifdef LOCAL
#include "debug.hpp"
#else
#define debug(...) 0
#define debug_itr(...) 0
#define debug_bits(...) 0
#endif

const ll mod = 998244353, N = 1e5 + 2;

void solve() {
  int n;
  cin >> n;
  int mx = -1;
  vector<int> a(n);
  for (int &i : a)
    cin >> i, mx = max(mx, i);
  int N = 1e6;

  vector<int> f(mx + 3);
  int mxx = 0;
  for (int &i : a) {
    f[i]++;
  }
  int l = 0, r = mx;
  while (l < r) {
    if (!f[l]) {
      if (l > (r + 1) / 2 - 1)
        break;
      f[l] = 1, f[r]--;
    }
    while (!f[r] && r > l)
      r--;
    l++;
  }
  debug(f);
  for (int i = 0; i <= mx + 1; ++i)
    if (!f[i]) {
      cout << i << el;
      break;
    }
}

int32_t main() {
  cin.tie(0)->sync_with_stdio(0);
  int t = 1;
  cin >> t;
  while (t--)
    solve();
#ifdef LOCAL
  debug((float)clock() / CLOCKS_PER_SEC);
#endif
  return 0;
}