#include <bits/stdc++.h>

using namespace std;

#define int long long
#define fi first
#define se second
#define endl '\n'

typedef pair<int,int> PII;

void solve(){
	int n;
	cin >>n;
	vector<int> fa(n + 1),d(n + 1);
	for(int i = 2;i <= n;i ++){
		int x;
		cin >>x;
		d[x] ++;
		fa[i] = x;
	}
	fa[1] = -1;
	queue<PII> q;
	vector<bool> st(n + 1);
	for(int i = 1;i <= n;i ++){
		if(!d[i]){
			q.push({fa[i],0});
		}
	}
	int ans = 0;
	while(!q.empty()){
		auto t = q.front();
		q.pop();
		int x = t.fi;
		if(st[x]){
			ans = max(ans,t.se + 1);
		}
		else{
			st[x] = true;
			ans = max(ans,t.se + 1);
			if(fa[x] != -1)q.push({fa[x],t.se + 1});
		}
	}
	cout<<ans<<'\n';
}

signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int T;
//	T = 1;
	cin >>T;
	while(T --){
		solve();
	}
}