#include <bits/stdc++.h>
#define int long long
#define pb push_back
bool debug=1;

#define dbg(x) if(debug)cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << endl
using namespace std;void ass(string err){cout<<err<<"\n";exit(0);}void ass(int err){cout<<err<<"\n";exit(0);}
typedef pair<int,int> pii;
const string COLOR_RESET = "\033[0m",  BRIGHT_CYAN = "\033[1;36m", NORMAL_FAINT = "\033[0;2m";
vector<int> a[100005 + 1];
int dfs(int u){
	vector<int> now;
	for(auto p:a[u]){
		now.pb(dfs(p));
	}
	sort(now.begin(), now.end());
	if(now.size()==0)
		return 1;
	if(now.size()==1)
		return now[0];
	return max(now[0],now[1] + 1);
}
void solve()
{
	ios::sync_with_stdio(false);cin.tie(0);mt19937_64 engie(202202052100238523);
	int n;
	cin>>n;
	for (int i = 0; i <= n;i++)
		a[i].clear();
	for (int i = 1; i <= n;i++){
		int u;
		cin>>u;
		a[u].pb(i);
	}
	cout<<dfs(1);
}

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	//freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
	int t=1;
	cin>>t;
	while(t--)
	{
		solve();
		cout << "\n";
	}
	return 0;
}

//__builtin_popcountl( ) 计算二进制1个数
//cout<<fixed<<setprecision(2);输出小数，四舍六入五取偶 
//__builtin_ctz( )返回末尾0的个数
//__builtin_clz( ) 返回前导0的个数
//__builtin_parity( )返回1的个数的奇偶性，偶数返回0
//__builtin_ffs( )返回最后一个1在第几位
//__builtin_sqrt( )快速开平方 
//stoll()字符串转为长整形
//点(x,y)的极角atan2(y,x)
//点(x,y)逆时针旋转A度，(x*cosA-y*sinA ,  x*sinA+y*cosA ) 
//C(n,k)+C(n,k-1)=(n+1,k)
//string s(str,stridx,strlen) //将字符串str内“始于stridx且长度顶多strlen”
//（从stridx开始往后strlen个字符）的部分作为字符串的初值
/*
int fp(int a,int b)
{
	int re=1;
	while(b)
	{
		if(b&1)re*=a;
		a*=a;re%=M;a%=M;
		b=b>>1;
	}
	return re;
}
*/