#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
using namespace std;

const int N = 2e5;

    int n, rt, p[N + 3];
    vector<int>g[N + 3];

bool cmp(int i, int j){
    return g[i].size() < g[j].size();
}

    int ans;

void dfs(int u, int x){
    ans = max(ans, x);
    for(int i = 0, v; i < g[u].size(); i++){
        v = g[u][i];

        if(i < g[u].size() - 1)
            dfs(v, x + 1);
        else 
            dfs(v, x);
    }
}

void sol(){
    scanf("%d", &n);
    for(int i = 1; i <= n; i++)
        g[i].clear();

    rt = -1;

    for(int i = 1; i <= n; i++){
        scanf("%d", &p[i]);
        g[p[i]].push_back(i);
        if(p[i] == 0)
            rt = i;
    }
    
    for(int i = 1; i <= n; i++)
        sort(g[i].begin(), g[i].end(), cmp);

    ans = 0;
    dfs(rt, 0);

    printf("%d\n", ans + 1);

}

int main(){
    int T;
    scanf("%d", &T);
    while(T--)
        sol();

    return 0;
}