#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int N = 3e5 + 10;

struct node {
	int id;
	int y;
};
vector<node>v[N];
int fa[N];
int n;
int ans;
bool cmp(node a, node b) {

	return a.y > b.y;
}
int cnt1;//总共的寄存器
int cnt2;//需要的寄存器

void dfs(int u) {
	if (v[fa[u]].size() == 0 && fa[u] != 0)cnt2--;
	cnt2++;
	if (cnt2 > cnt1)cnt1++;
	if (v[u].size() == 0)cnt2--;
	while (v[u].size()) {
		auto x = v[u][v[u].size() - 1].id;
		v[u].pop_back();
		dfs(x);
	}

}
int main() {
	int t;
	cin >> t;
	while (t--) {
		memset(fa, 0, sizeof fa);
		cnt1 = 0;//总共的寄存器
		cnt2 = 0;//需要的寄存器
		ans = 0;
		int root = -1;
		cin >> n;
		for (int i = 1; i <= n; i++) {
			int x;
			cin >> x;
			if (x == 0)root = i;

			else {
				fa[i] = x;
				v[x].push_back({ i,0 });
			}
		}
		for (int i = 1; i <= n; i++) {
			for (int j = 0; j < v[i].size(); j++) {
				v[i][j].y = v[v[i][j].id].size();
			}
		}
		for (int i = 1; i <= n; i++) {
			sort(v[i].begin(), v[i].end(), cmp);
		}
		cnt1 = 1;
		cnt2 = 0;
		dfs(root);
		cout << cnt1 << endl;
	}
	return 0;
}