/* -*- coding: utf-8 -*-
 *
 * 3780.cc:  No.3780 Erase and Mex - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 200000;
const int INF = 1 << 30;

/* typedef */

template <typename T>
struct SegTreeMinDelay {
  int e2;
  vector<T> nodes, dls;
  T defv;
  SegTreeMinDelay() {}

  void init(int n, T _defv) {
    defv = _defv;
    for (e2 = 1; e2 < n; e2 <<= 1);
    nodes.assign(e2 * 2, defv);
    dls.assign(e2 * 2, 0);
  }

  T &geti(int i) { return nodes[e2 - 1 + i]; }
  void seti(int i, T v) { geti(i) = v; }

  void setall() {
    for (int j = e2 - 2; j >= 0; j--)
      nodes[j] = min(nodes[j * 2 + 1], nodes[j * 2 + 2]);
  }

  void __update(int k) {
    if (dls[k] != 0) {
      int k0 = k * 2 + 1, k1 = k0 + 1;
      nodes[k0] += dls[k];
      nodes[k1] += dls[k];
      dls[k0] += dls[k];
      dls[k1] += dls[k];
      dls[k] = 0;
    }
  }

  void add_range(int r0, int r1, T v, int k, int i0, int i1) {
    if (r1 <= i0 || i1 <= r0) return;
    if (r0 <= i0 && i1 <= r1) {
      nodes[k] += v;
      dls[k] += v;
      return;
    }

    __update(k);

    int im = (i0 + i1) / 2;
    int k0 = k * 2 + 1, k1 = k0 + 1;
    add_range(r0, r1, v, k0, i0, im);
    add_range(r0, r1, v, k1, im, i1);
    nodes[k] = min(nodes[k0], nodes[k1]);
  }
  void add_range(int r0, int r1, T v) { add_range(r0, r1, v, 0, 0, e2); }

  T min_range(int r0, int r1, int k, int i0, int i1) {
    if (r1 <= i0 || i1 <= r0) return defv;
    if (r0 <= i0 && i1 <= r1) return nodes[k];

    __update(k);

    int im = (i0 + i1) / 2;
    T v0 = min_range(r0, r1, k * 2 + 1, i0, im);
    T v1 = min_range(r0, r1, k * 2 + 2, im, i1);
    return min(v0, v1);
  }
  T min_range(int r0, int r1) { return min_range(r0, r1, 0, 0, e2); }
};

/* global variables */

int as[MAX_N], cs[MAX_N];
SegTreeMinDelay<int> st;

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n; i++) scanf("%d", as + i);

    if (n == 1) { printf("%d\n", as[0]); continue; }

    fill(cs, cs + n, 0);
    for (int i = 0; i < n; i++) cs[(as[i] < n) ? as[i] : 0]++;
    
    st.init(n + 1, INF);
    for (int i = 0; i < n; i++) st.seti(i, cs[i]);
    st.seti(n, 0);
    st.setall();

    int maxx = 0;
    int zc = 0, rc = n;
    while (rc > 0) {
      //printf(" zc=%d, rc=%d\n", zc, rc);
      //for (int i = 0; i < n; i++) printf(" %d", st.min_range(i, i + 1));
      //putchar('\n');
      
      if (st.min_range(0, 1) == 0) {
	st.add_range(0, 1, 1);
	zc++;
      }
      else {
	int x0 = 0, x1 = n + 1;
	while (x0 + 1 < x1) {
	  int x = (x0 + x1) / 2;
	  if (st.min_range(0, x) > 0) x0 = x;
	  else x1 = x;
	}
	//printf("  x0=%d\n", x0);
	if (x0 > rc) break;

	st.add_range(0, x0, -1);
	st.add_range(x0, x0 + 1, 1);
	maxx = max(maxx, x0);
	rc += -x0 + 1;
      }
    }

    printf("%d\n", maxx);
  }

  return 0;
}