#include <bits/stdc++.h>

using namespace std;

template <unsigned M_> struct ModInt {
    static constexpr unsigned M = M_;
    unsigned x;
    constexpr ModInt() : x(0) {}
    constexpr ModInt(unsigned x_) : x(x_ % M) {}
    constexpr ModInt(unsigned long long x_) : x(x_ % M) {}
    constexpr ModInt(int x_) : x(((x_ %= static_cast<int>(M)) < 0) ? (x_ + static_cast<int>(M)) : x_) {}
    constexpr ModInt(long long x_) : x(((x_ %= static_cast<long long>(M)) < 0) ? (x_ + static_cast<long long>(M)) : x_) {}
    ModInt &operator+=(const ModInt &a) {
        x = ((x += a.x) >= M) ? (x - M) : x;
        return *this;
    }
    ModInt &operator-=(const ModInt &a) {
        x = ((x -= a.x) >= M) ? (x + M) : x;
        return *this;
    }
    ModInt &operator*=(const ModInt &a) {
        x = (static_cast<unsigned long long>(x) * a.x) % M;
        return *this;
    }
    ModInt &operator/=(const ModInt &a) { return (*this *= a.inv()); }
    ModInt pow(long long e) const {
        if (e < 0)
            return inv().pow(-e);
        ModInt a = *this, b = 1;
        for (; e; e >>= 1) {
            if (e & 1)
                b *= a;
            a *= a;
        }
        return b;
    }
    ModInt inv() const {
        unsigned a = M, b = x;
        int y = 0, z = 1;
        for (; b;) {
            const unsigned q = a / b;
            const unsigned c = a - q * b;
            a = b;
            b = c;
            const int w = y - static_cast<int>(q) * z;
            y = z;
            z = w;
        }
        assert(a == 1);
        return ModInt(y);
    }
    ModInt operator+() const { return *this; }
    ModInt operator-() const {
        ModInt a;
        a.x = x ? (M - x) : 0;
        return a;
    }
    ModInt operator+(const ModInt &a) const { return (ModInt(*this) += a); }
    ModInt operator-(const ModInt &a) const { return (ModInt(*this) -= a); }
    ModInt operator*(const ModInt &a) const { return (ModInt(*this) *= a); }
    ModInt operator/(const ModInt &a) const { return (ModInt(*this) /= a); }
    template <class T> friend ModInt operator+(T a, const ModInt &b) { return (ModInt(a) += b); }
    template <class T> friend ModInt operator-(T a, const ModInt &b) { return (ModInt(a) -= b); }
    template <class T> friend ModInt operator*(T a, const ModInt &b) { return (ModInt(a) *= b); }
    template <class T> friend ModInt operator/(T a, const ModInt &b) { return (ModInt(a) /= b); }
    explicit operator bool() const { return x; }
    bool operator==(const ModInt &a) const { return (x == a.x); }
    bool operator!=(const ModInt &a) const { return (x != a.x); }
    friend std::ostream &operator<<(std::ostream &os, const ModInt &a) { return os << a.x; }
};

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using ll = long long;
// using mint = ModInt<1000000007U>;
using mint = ModInt<998244353U>;

void solve() {
    int n;
    cin >> n;
    vector<vector<int>> g(n + 1);
    for (int i = 1; i <= n; i++) {
        int p;
        cin >> p;
        g[p].push_back(i);
    }
    vector<int> dp(n + 1);
    auto dfs = [&](auto self, int v) -> void {
        int mx1 = -1, mx2 = -1;
        for (int u : g[v]) {
            self(self, u);
            if (dp[u] > mx1) {
                mx2 = mx1;
                mx1 = dp[u];
            } else if (dp[u] > mx2) {
                mx2 = dp[u];
            }
        }
        if (mx1 == -1)
            dp[v] = 1;
        else if (mx2 == -1)
            dp[v] = mx1;
        else
            dp[v] = max(mx1, mx2 + 1);
    };
    dfs(dfs, 1);
    cout << dp[1] << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    cin >> T;
    for (int tc = 1; tc <= T; tc++) {
        solve();
    }
    return 0;
}