#include <bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;
using ll = long long;
const int N = 2000010, MOD = 998244353, INF = 0x3f3f3f3f;
int n, m, w[N];


bool check(int mid, vector<int> c) {
	int ne = 1;
	for (int i = n + 30; i > mid - 1; i--) c[0] += c[i];
	for (int i = mid - 1; ~i; i--) {
		if (c[i] >= ne) {
			c[0] += c[i] - ne;
		} else {
			if (i == 0) return 0;
			ne += ne - c[i];
			if (ne > n && i) return 0;
		}
	}
	return 1;
}

void solve() {
	scanf("%d", &n);
	if (n == 1) {
		scanf("%d", w + 1);
		printf("%d\n", max(1, w[1]));
		return;
	}
	vector<int> c(n + 31);
	for (int i = 1; i < n + 1; i++) {
		scanf("%d", w + i), w[i] = min(w[i], n + 30);
		c[w[i]]++;
	}
	int l = 1, r = n + 30;
	while (l < r) {
		int mid = l + r + 1 >> 1;
		if (check(mid, c)) l = mid;
		else r = mid - 1;
	}
	printf("%d\n", l);
}

int main() {
	int T = 1;
	scanf("%d", &T);
	while (T--) solve();
	return 0;
}