#include<bits/stdc++.h>
#define LL long long
using namespace std;
const int N=1.1e6;
inline LL read(){
	LL x=0,ff=1;
	char c=getchar();
	while(!isdigit(c)&&c!='-') c=getchar();
	if(c=='-') c=getchar(),ff=-1;
	while(isdigit(c)) x=x*10ll+c-'0',c=getchar();
	return x*ff;
}
int n;
int head[N],to[N*2],nxt[N*2],tot;
void add_edge(int x,int y){
//	cerr<<"edge:"<<x<<" "<<y<<endl;
	++tot;
	to[tot]=y;
	nxt[tot]=head[x];
	head[x]=tot;
}
int f[N],ans;
void dfs(int x){
	if(!head[x]){
		f[x]=0;
//		cerr<<x<<" "<<f[x]<<endl;
		return ;
	}
	f[x]=n+1;
	for(int i=head[x];i;i=nxt[i]){
		int y=to[i];
		dfs(y);
		f[x]=min(f[x],f[y]+1);
		ans=max(f[y]+1,ans);
	}
//	cerr<<x<<" "<<f[x]<<endl;
}
int main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	int casecnt=read();
	while(casecnt--){
		ans=0;
		n=read();
		for(int i=1;i<=n;++i)
			head[i]=0;
		tot=0;
		for(int i=2;i<=n;++i){
			int x=read();
			add_edge(x,i);
		}
		dfs(1);
		printf("%d\n",ans);
	}
	return 0;
}