#include "bits/extc++.h"

using namespace std;

template <typename T>
void dbgh(const T& t) {
    cerr << t << endl;
}

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t << " | ";
    dbgh(u...);
}

#ifdef DEBUG
#define dbg(...)                                           \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
         << ": ";                                          \
    dbgh(__VA_ARGS__)
#else
#define cerr   \
    if (false) \
    cerr
#define dbg(...)
#endif

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

constexpr int maxn = 2e5 + 5;

vector<int> graph[maxn];

int dfs(int u) {
    if (!sz(graph[u])) {
        return 1;
    }
    vector<int> chv;
    for (auto& v : graph[u]) {
        chv.push_back(dfs(v));
    }
    if (sz(chv) == 1) {
        return chv[0];
    }
    sort(begin(chv), end(chv));
    return max(1 + end(chv)[-2], chv.back());
}

void solve() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        graph[i].clear();
    }
    for (int i = 0; i < n; i++) {
        int p;
        cin >> p;
        p--;
        if (i) {
            graph[p].push_back(i);
        }
    }
    cout << dfs(0) << endl;
}

int main() {
    cin.tie(nullptr);
    cin.exceptions(ios::failbit);
    ios_base::sync_with_stdio(false);
    int tcs;
    cin >> tcs;
    while (tcs--) {
        solve();
    }
}