#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    int a[n];
    for (int i = 0; i < n; i++) cin >> a[i];
    int m = 0, k = 0;
    sort(a, a + n);
    for (int i = 0; i < n; i++) {
      if (a[i] == m)
        m++;
      else if (a[i] == k)
        k++;
    }
    cout << m + k << endl;
  }
}
