#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve() {
    int n;
    cin >> n;

    vector<vector<int> > edge(n + 1);
    vector<int> fa(n + 1);
    int st;
    for (int i = 1; i <= n; ++i) {
        int x;
        cin >> x;
        if (x) {
            fa[i] = x;
            edge[x].push_back(i);
        } else {
            st = i;
        }
    }

    vector<int> num(n + 1);
    // int ans = 0;
    auto dfs = [&](auto &&self, int u) -> void {
        int maxx = 0, maxcnt = 0;
        for (auto v : edge[u]) {
            self(self, v);
            if (num[v] > maxx) {
                maxx = num[v];
                maxcnt = 1;
            } else if (num[v] == maxx) {
                maxcnt++;
            }
        }
        if (maxcnt != (int)edge[u].size() || (maxcnt == (int)edge[u].size() && maxcnt == 1)) {
            num[u] = maxx;
        } else {
            num[u] = maxx + 1;
        }
    };

    dfs(dfs, st);

    cout << num[st] << '\n';
}

int main() {
    cin.tie(nullptr) -> sync_with_stdio(false);

    int _;
    cin >> _;
    while (_--) solve();

    return 0;
}
/*
2
3
0 1 2
7
0 1 2 2 1 4 1
*/
/*
1
4
0 1 2 2 
*/
/*
1
7
0 1 1 3 1 5 5
*/