#include<cstdio>
#include<algorithm>
struct celula{
	long inf;
	celula *leg;
}*a[101000],*p;
long i,test,k,n,x,y;
bool desc(long a,long b){
	if(a>b)return 1;
	else return 0;
}
long df(long x){
	long t[100000],m=0,q;
	p=a[x];
	while(p!=0){
		t[q++]=df(p->inf);
		p=p->leg;
	}
	std::sort(t,t+q,desc);
	for(k=0;k<q;k++)
		if(t[k]+k>m)m=t[k]+k;
	return m;
}
int main(){
	freopen("zvon.in","r",stdin);
	freopen("zvon.out","w",stdout);
	scanf("%ld",&test);
	for(i=0;i<test;i++){
		scanf("%ld",&n);
		for(k=0;k<n;k++)
			a[k]=0;
		for(k=0;k<n-1;k++){
			scanf("%ld%ld",&x,&y);
			p=new celula;
			p->inf=y;p->leg=a[x];a[x]=p;
		}
		printf("%ld\n",df(1));
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}