#include <bits/stdc++.h>
using namespace std;
template <class L, class R>
ostream& operator<<(ostream& os, pair<L, R> P) {
  return os << "(" << P.first << "," << P.second << ")";
}
template <class T>
ostream& operator<<(ostream& os, vector<T> V) {
  os << "[ ";
  for (auto v : V) os << v << " ";
  return os << "]";
}
template <class T>
ostream& operator<<(ostream& os, set<T> second) {
  os << "{ ";
  for (auto s : second) os << s << " ";
  return os << "}";
}
template <class L, class R>
ostream& operator<<(ostream& os, map<L, R> M) {
  os << "{ ";
  for (auto m : M) os << "(" << m.first << " : " << m.second << ") ";
  return os << "}";
}
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cout << name << " : " << arg1 << '\n';
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " |";
  __f(comma + 1, args...);
}
void solve() {
  map<int, int> cnt;
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    int x;
    cin >> x;
    cnt[x]++;
  }
  int a = -1;
  for (int i = 0; i <= 101; ++i) {
    if (cnt[i] == 0) {
      cout << i + (a == -1 ? i : a) << '\n';
      return;
    } else if (cnt[i] == 1 and a == -1) {
      a = i;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int T = 1, tc = 1;
  cin >> T;
  while (T--) {
    solve();
  }
  return 0;
}
