#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt;
  cin >> tt;
  while (tt--) {
    int n;
    cin >> n;
    VI a(n);
    rep(i, n) cin >> a[i];
    if (n == 1) {
      cout << max(a[0], 1) << '\n';
      continue;
    }
    VI freq(n + 1);
    for (int x : a) {
      if (x < n) freq[x]++;
      else freq[0]++;
    }
    int l = 0, r = n + 1;
    while (r - l > 1) {
      int c = (l + r) / 2;
      auto f = freq;
      for (int i = c; i <= n; i++) f[0] += f[i], f[i] = 0;
      int req = 1;
      for (int i = c - 1; i >= 1; i--) {
        int t = min(req, f[i]);
        int rest = req - t;
        req += rest;
        f[0] += f[i] - t;
        f[i] = 0;
        if (req > n) break;
      }
      (req <= f[0] ? l : r) = c;
    }
    cout << l << '\n';
  }
}