//Make CSP great again
//Vengeance
#include <bits/stdc++.h>
#define TASK "TESTCODE"
using namespace std;
const int N = 2e5;
vector<int> adj[N + 1];
int res, n, dp[N + 1];
void read()
{
    cin >> n;
    for (int i = 0; i <= n; ++ i)
    {
        adj[i].clear();
        dp[i] = 0;
    }
    for (int i = 1; i <= n; ++ i)
    {
        int p;
        cin >> p;
        adj[p].push_back(i);
    }
}
void DFS(int u)
{
    vector<int> x;
    for (int v : adj[u])
    {
        DFS(v);
        x.push_back(dp[v]);
    }
    if (adj[u].empty())
    {
        dp[u] = 1;
        return ;
    }
    sort(x.begin(), x.end());
    dp[u] = x.back();
    if (x.size() > 1)
    {
        dp[u] = max(dp[u], dp[x[x.size() - 2]] + 1);
    }
}
void solve()
{
    DFS(0);
    cout << dp[0] << '\n';
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".OUT", "w", stdout);
    }
    int t = 1;
    bool typetest = true;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        //cout << "Case " << __ << ": ";
        read();
        solve();
    }
}