#include<stdio.h>
int a[200005];
int cnt[200005];
void solve()
{
	int n;
	scanf("%d", &n);
	int i;
	for (i = 0; i < n; i++)
		scanf("%d", &a[i]);
	if (n == 1)
	{
		if (a[0] > 0)
			printf("%d\n", a[0]);
		else
			printf("1\n");
		return;
	}
	int min, mid, max;
	min = 0;
	max = n + 1;
	int m;
	while (max - min > 1)
	{
		mid = (max + min) / 2;
		for (i = 0; i < mid; i++)
			cnt[i] = 0;
		for (i = 0; i < n; i++)
		{
			if (a[i] < mid)
				cnt[a[i]]++;
			else
				cnt[0]++;
		}
		m = 1;
		for (i = mid - 1; i > 0; i--)
		{
			if (cnt[i] > m)
			{
				cnt[0] += cnt[i] - m;
			}
			else
			{
				m += m - cnt[i];
			}
		}
		if (cnt[0] < m)
			max = mid;
		else
			min = mid;
	}
	printf("%d\n", min);
	return;
}
int main()
{
	int T;
	scanf("%d", &T);
	for (; T > 0; T--)
		solve();
	return 0;
}