#include <bits/stdc++.h>
#define pb push_back

using namespace std;

ifstream fin("zvon.in");
ofstream fout("zvon.out");

const int NMAX = 1e5 + 5;
vector<int>g[NMAX];
bitset<NMAX>vis;
int d[NMAX];
int t;
void bfs(int x){
  queue<int>Q;
  Q.push(x);
  vis[x]=1;
  d[x]=1;
  while(!Q.empty()){
    int nod=Q.front();
    Q.pop();
    for(auto i:g[nod]){
        if(!vis[i]){
          d[i]=d[nod]+1;
          Q.push(i);
        }
    }
  }
}
int main(){
 fin>>t;
 while(t--){
    int n,x,y;
    fin>>n;
    if(n==1){
        fout<<0<<"\n";
        continue;
    }
    for(int i=1;i<n;++i){
        fin>>x>>y;
        g[x].pb(y);
    }
    vis.reset();
    memset(d,0,sizeof(d));
    bfs(1);
    int ct=0,m=0;
    for(int i=1;i<=n;++i)
        if(g[i].size()==0)
          m=max(m,d[i]);
    fout<<m<<"\n";
 }
 return 0;
}