#include <bits/stdc++.h>
using namespace std;
vector mp(0,vector (0,0));
vector deep(0,0);
int mxd=0;
void dfs(int d,int fa){
	for(auto x:mp[d]){
		if(x==fa) continue;
		deep[x]=deep[d]+1;
		if(deep[x]>deep[mxd]) mxd=x;
		dfs(x,d);
	}
}
void solve(){
	int n;
	cin>>n;
	mp.assign(n+1,vector<int>(0));
	for(int i=2;i<=n;i++){
		int x;
		cin>>x;
		mp[x].push_back(i);
//		mp[i].push_back(x);
	}
	mxd=1;
	deep.assign(n+1,0);
	deep[1]=0;
	dfs(1,0);
//	int tp=mxd;
//	deep[tp]=1;
//	deep.assign(n+1,0);
//	dfs(tp,0);
//	cout<<tp<<' '<<mxd<<' '<<deep[mxd]<<'\n';
	cout<<deep[mxd]<<'\n';
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int ins=1;
	cin>>ins;
	while(ins--) solve();
	return 0;
}