#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxN=200010;

int maxnum[maxN];
vector<int> edge[maxN];

bool dfs(ll x,ll fa)
{
    if(edge[x].size()==1) return 0;
    ll tmp=0;
    for(auto i:edge[x])
    {
        if(i==fa) continue;
        if(dfs(i,x)) tmp++;
    }
    if(edge[x].size()>2) maxnum[x]=max(maxnum[x],1); 
    //cout<<x<<"~~~"<<maxnum[x]<<endl;
    maxnum[fa]=max(maxnum[fa],maxnum[x]+(tmp>1?1:0));
    if(edge[x].size()>2) return 1;
    else return 0;
}

void solve()
{
    int n,thefa;
    cin>>n;
    edge[0].push_back(0);
    for(int i=1;i<=n;i++)
    {
        cin>>thefa;
        edge[i].push_back(thefa);
        edge[thefa].push_back(i);
    }
    dfs(0,0);
    cout<<maxnum[0]+1<<endl;
    for(int i=0;i<=n;i++)
    {
        maxnum[i]=0;
        edge[i].clear();
    }
    return;
}

int main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int T; cin>>T;
    while(T--) solve();
    return 0;
}